Problems with 3rd party Lockscreen-Apps

Dear friend,
Thanks for the great Fairphone 2 to the Fairphone-Team. I love it . Good job!
However, I have a problem with an app : I don’t like the default lock screen . That’s why I installed the app "Hi Locker ". If I reboot the device, it often happens that the Fairphone obviously does not know which lock screen is to use and it begins to switch frantically between the default screen and the “hi locker”-screen. Meanwhile it is not usable. Only after one or two repeated reboots is it functional again. What can I do? Have someone experience with this App or a recommendation for another App?
Thanks and best regards !

Did you disable all standard locking methods in Settings > Security

No, it isn’t possible to disable the locking methods “wiping” (wischen).

I have a similar problem with Locker Master (on a FP2). I was able to switch off the standard lockscreen swipe, and it worked perfectly… until I rebooted my phone. I wasn’t able to give in my pin code (because the standard lock screen was switched off, I guess).

I also tried GO Locker, but this app made my phone crash.

Would there be a way to make this work?

I’m having the same issue. I’m trying to use zui locker, but every boot both zui and the default locker start. I tried with other lockers and the same happened with solo locker and hi locker. The issue does not occur every time, but quite often.
I know I should disable the default locker before installing a new one, but, as you, I cannot find the “none” option.

Also, searching on Google it seems like clearing the credentials in security settings could fix this problem (unblock the None option), but “clear credentials” is greyed out in my settings.

I’m using fp2 open os (latest release) with xprivacy.

Could you solve this issue on your phone?