iOS app stuck app login

Expected behaviour

Register app pass
Open iOS app
Enter and grant
Login

NOTE all other access types work, (Firefox & Chrome browsers, Android app)

Actual behaviour

Stuck

The “grant accessory button clicks but doesn’t do anything

Steps to reproduce

Login to server and add app decide for my user

Open in iOS and try to authgrant

iOS version

13.1.2

App version

2.24.1

Server configuration

URL is something like https://my domain.blah.ca/cloud

$ sudo cat /srv/nextcloud/config/config.php
<?php
$CONFIG = array (
  'instanceid' => 'SNIP',
  'passwordsalt' => 'SNIP',
  'secret' => 'SNIP',
  'trusted_domains' => 
  array (
    0 => 'nextcloud',
    1 => 'SNIP.homenode.ca',
  ),
  'trusted_proxies' => 
  array (
    0 => '10.0.0.52',
  ),
  'overwritehost' => 'SNIP.homenode.ca',
  'overwriteprotocol' => 'https',
  'overwritewebroot' => '/cloud',
  'overwritecondaddr' => '^10\\.0\\.0\\.52$',
  'datadirectory' => '/opt/nextcloud/',
  'dbtype' => 'mysql',
  'version' => '14.0.4.2',
  'overwrite.cli.url' => 'https://nextcloud',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nextcloud_admin',
  'dbpassword' => 'SNIP',
  'installed' => true,
  'theme' => '',
  'loglevel' => 2,
  'maintenance' => false,
  'updater.release.channel' => 'stable',
);

Operating system: linux

Linux nextcloud 4.4.0-164-generic #192-Ubuntu SMP Fri Sep 13 12:02:50 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/issue
Ubuntu 16.04.5 LTS \n \l

Web server:

Apache apache2 2.4.18-2ubuntu3.13

$ cat /etc/apache2/sites-enabled/nextcloud.conf 
Alias / "/srv/nextcloud/"

<Directory /srv/nextcloud/>
  Options +FollowSymlinks
  AllowOverride All

 <IfModule mod_dav.c>
  Dav off
 </IfModule>

 SetEnv HOME /srv/nextcloud
 SetEnv HTTP_HOME /srv/nextcloud

 Satisfy Any

</Directory>

• a reverse proxy (10.0.0.52) in front of it

# Nextcloud ("nextcloud" is the local hostname which resolves to 10.0.0.55)
ProxyPass /cloud https://nextcloud:443
ProxyPassReverse /cloud https://nextcloud:443
# https://docs.nextcloud.com/server/14/admin_manual/issues/general_troubleshooting.html#service-discovery
Redirect 301 /.well-known/carddav /cloud/remote.php/dav
Redirect 301 /.well-known/caldav /cloud/remote.php/dav

Database:
N/A

PHP version:
php7.0-common 7.0.33-0ubuntu0.16.04.7

Nextcloud version: (see Nextcloud admin page)

• 14.0.4

No source file or test is named. Start by reproducing the login and grant-access flow on iOS 13.1.2 with app version 2.24.1 against the reverse-proxied Nextcloud setup, comparing it with the working browser and Android flows. Done means the Grant accessory action completes authentication instead of leaving the app stuck.