Hang tight, and do not delete app. I need to head to bed here but we will be looking into this tomorrow. If you get a popup to share the log please send it along. If not we will need to sign you up for a TestFlight beta to address this.
Follow Instructions laid out here: Do NOT delete your app if it crashes and other migration updates - #60 by cherian
Jan 11th update: Do NOT delete your app if it crashes and other migration updates - #181 by phillryu
TestFlight is available. I’ll try to figure it out.
P.S. There is no window. it just crashes.
I’ve lost hundreds of list entries in 10 lists!!
The same happened to me! 
Update for people reading from the top:
Try force quitting/relaunching Clear. See if you can find your lists in ‘My Lists’ or the Archive. (To back out and navigate inside the app, tap near the bottom center of your screen)
If your Clear is crashing on launch hang tight, we are debugging this and preparing a TestFlight diagnostics build and expect to get to the bottom of it.
If you have iCloud full device backups on… know that it does contain your list data if you had previously been using Clear on that device. I cannot recommend everyone simply restoring to before launch day as a way to recover data quite yet but:
If you are a beta tester who experienced data loss, restoring your device from backup before launch, and then installing/running release version of Clear does seem to work for several testers so far.
For everyone else, especially longtime Clear 1.x listers we hope to have this diagnostics TestFlight build to send out to you later today or tomorrow at the latest, it will not fix this but really help us figure out the situation for each of you. Also please either post here, or email clear@impending.com so we can track you and get back to you as we figure this situation out further.
/end update
Hey guys, we’re going to be debugging this today. Your installed Clear still has the data there, even it cannot read it, so I am hopeful we can recover. Merging this thread into another one yesterday to keep you all in one place.
Couple quick questions – were you running the beta before? And is there any lists stored in your Archive in the new release version?
In my case I was running the beta before and, as soon as I installed the release version, the beta stopped working. I then opened the release version and my list was there and imported automatically.
I deleted the beta (as it didn’t work anymore) but when I reopened the release version, my list was gone.
Regarding archive, it’s not there either.
Ok appreciate the extra details. We’ll be looking into this as a team in about a couple hours when everyone is on.
Heeeeeeeelp I also upgraded and lost all my lists!!! Wtf guys??? There are notifications that they are still there but I cant find it anywhere inside the app.
Guys please fix this! I shouldnt have updated! Damn….
Guys please help us recovering our lists, I have more than 10 years using your App, this never happen before. It is very important for me !
check your archive? some people are finding their lists there
I have been using this for probably 10 years and have loved it. This morning I got an automatic update on my iPhone and iPad and since then it just doesn’t work. I hope this is not a beta that got automatically downloaded.
Not in my case, not showing anything in archive.
I got a message saying your lists have been imported but that was it …. And im not able to find them
Will the lists from beta transfer too?
Same exact thing for me. Not only that but all my legacy themes from years ago ZAP gone.
Kinda sucks because I’d tested clear so much I’d unlocked nearly everything possible over time.
Not bitching just bringing it up for awareness 
Incredible! Everything deleted, no instructions, just a page of default lists. No help menu. No setup page. I waited a long time for the update. Astonishingly incompetent rollout. I’m looking elsewhere, after years of being perfectly happy with the app.
Please hold on tight. We are working on a diagnostic mechanism. You should hear from us soon.
Is there any other place we can access our old lists? Have years of information on this and now just gone all of sudden with this new install. So knowing they are still safe, and you are working on a solve would be really helpful to hear!
Hi all, this is our main priority for the rest of today. Your data is still stored in the new Clear as it was before, so even if there are issues reading it, it should in theory still be there with recovery options. (Do not delete the app!)
I have a couple questions and this support URL to try using on the updated Clear:
If you are able to please send me that log. If not, hang tight and we will be looking into a TestFlight build to invite you to more designed to figure this out.
In addition there are a couple sanity checks that might be worth asking or trying:
• One is if you were beta testing, check the Archive in the release version in case they were imported there
• The other question is for the people who had old lists come into release Clear, were you previously using Clear on multiple devices and its syncing function?
1 - No.
2 - No. One device.
All my data for the last 10 years has been deleted since the new update as of 16 hours ago? Why ? I hope this is fixed as this is not acceptable.