Does the problem persist in another apps or only in this one? How long ago was your app created?
Please Sergey edit your answer to ommit the name of the app. You can use APP_ID.
The app was created a couple of days previous to the end of the migration period around november. The functionality has been working without problem during weeks.
It stopped working after I created this thread regarding the problem with the threshold limits not cleared. (Don’t know if it’s related though).
As I mentioned before, it happened with another app as well. I haven’t tried with all of them because I don’t “delete all” every day, 
For your convenience I’m checking and it happens in:
FAAC6BED-DDD1-AFF4-FF65-D5717185BD00
65520AD3-5B8D-09E3-FFD8-BD5A81895700
071BE2D1-F15B-A3B0-FF63-3EEBEF9F0300
So basically in all the apps that I created around november.
I created an app 1-2 weeks ago to not be deleting my users data to test Delete all (369E3769-779B-EEE0-FF64-68B189FF5200) and in this one the feature works well.
Just FYI it’s kind of disturbing that the apps present different behaviour if this issue is not happening to other users.
Let me know if I can help with anything else
Were these apps created through a migration from 3.x? I mean, have you imported the migration archives from 3.x to them?
I followed the migration process as stated in the instructions. That included the import stage.
As I said before, the “Delete all” feature worked in all of them at least 2 weeks ago. Not sure when exactly stopped working but for sure it was working on New Year for instance.
The migration was performed in November.
Thank you for all the information! I now found that there is a bug during migration, which only became affecting this functionality after a server update a few weeks ago. I have already created internal tasks to fix this in all apps: BKNDLSS-16527 and BKNDLSS-16528.
We shall notify you here as soon as we have any news.
I guess this issue affect any app under the same conditions, isn’t it?
Yes, any app on which a migration import has been run.
Ok, BTW, Is it the threshold limit solved ? (BKNDLSS-16466.)
Yes, this one is solved. The Delete All operation now clears the cache properly, so the usage becomes correct immediately after that.
I have fixed your four apps manually, so there should be no problems with Delete All anymore in them. Unfortunately you still can’t test it on any other migrated apps due to the new issues mentioned above. They will be fixed a bit later when we deploy a general fix to the server.