remote wipe doesn't wipe correctly and never finishes

So, I wanted to remote wipe my mobile to get rid of the old configuration and re-organize my file structure.
Hence I did in the browser:
1. deselect "Allow filesystem access" for my mobile (to prevent messing with my files and block auto-upload)
2. select "Remote wipe" for your mobile (one day later, I decided to wipe it to create a new, clean, config for stuff like auto-upload)
3. The device is marked for a remote wipe but doesn't wipe itself. For comparison: My Tablet (Desktop-Client) did complete the wipe within a minute or so [marked at the same time]. Both devices were only before I marked them.

[days later]: notification "remote wipe started for -myMobile-" (finally).
But… it never finished…
*[some days passed already again]*

To conclude (Actual behavior):
- The mobile device doesn't wipe itself (well, wipe all nextcloud data and caches; it's not a complete device wipe after all).
- I can still see and navigate the cached file hierarchies
- Occasionally the app shows me the login page (to enter the server address). However, with a simple "back button" press, I can go back. The App shows my account as login-ed…
- Due to mass-login attempts the server eventually disabled my account (kinda funny…)

### Expected behavior
- all nextcloud data should be wiped from the device → cached files and cached folder hierarchies
- it shouldn't be possible to view any previous screen (/ to navigate back from the login screen)
- device should inform the server correctly about wipe start and wipe completed (Though, as the wipe didn't end 'correctly' this might behave correctly already…)

### Can you reproduce this problem on https://try.nextcloud.com?
Didn't tried yet. I wanted to check back whether there might be some more useful information I could give here before I hard-reset the app. Additionally, I can't imagine any server setup preventing the remote wipe. It works with other devices fine after all.

### Environment data
Android version: 9
Device model: H3113
Stock or customized system: stock
Nextcloud app version: 3.18.0
Nextcloud server version: 21.0.7
Reverse proxy: caddy
### Logs

#### Nextcloud log (data/nextcloud.log)
Just stuff like "Login failed for xxxx" (because obviously, the token isn't valid anymore).