Nextcloud Mobile iOS app keeps asking for password

Expected behaviour

Expected behavior is to enter login credentials and to be taken into app

Actual behaviour

I’m having problems logging in with the mobile iOS app (I’m not having any problems logging in from computer or through browser on the iphone – just the mobile nextcloud iOS app). I enter credentials and for a brief second I can see the files list and then I’m taken back to the login screen. It keeps occurring over and over again

Steps to reproduce

See above

iOS version

12.1.4

App version

2.22.8

Server configuration

Operating system:
FreeNAS 11.2-Release UI running within freebsd jail 11.2-Release p!

Web server:
Apache webserver Apache/2.4.38 (FreeBSD)

Database:
10.2.21-MariaDB

PHP version:
PHP 7.2.14 (cli) (built: Feb 7 2019 01:24:31) ( NTS )

Nextcloud version: (see Nextcloud admin page)
15.04

Nextcloud log files:
{"reqId":"XykabxYmbeC4ugWTfUPk","level":2,"time":"2019-02-15T15:50:24+00:00","remoteAddr":"24.13.24.199","user":"--","app":"core","method":"GET","url":"/index.php/login/flow","message":"Renewing session token failed","userAgent":"Mozilla/5.0 (iOS) Nextcloud-iOS/2.22.8","version":"15.0.4.0"}

Issue also reported here (wasn't sure what proper channel was most appropriate): https://help.nextcloud.com/t/nextcloud-mobile-ios-app-keeps-asking-for-password/47668

Start by reproducing the login loop in the iOS app using the reported iOS 12.1.4 and app 2.22.8 environment, then inspect handling around the /index.php/login/flow request and the “Renewing session token failed” log. Done means valid credentials keep the user signed in and the files list remains accessible instead of returning to the login screen.