This is getting off-topic in this thread (better in Openrepos-thread), but I can confirm the problems (or "oddities" or whatever you want to call it) in Warehouse app and also using pkcon update:

Since some point a few weeks ago (I THINK this was already before OS update), Warehouse (and also "pkcon refresh && pkcon update) don't show any available updates. Warehouse app shows the "Updates available" remorse timer, but clicking on it shows a blank update page ("queue is empty").
When I then open open the "recent updates" page and click on a recently changed app that I have installed on my system, the app's description page shows me that a newer version of the app is available, giving me the option to upgrade.

I can reproduce that e.g. with the "search engines for Sailfish browser" app that was posted as an example before.
Repository is enabled.

This is not only one app, but apparently ALL apps installed from openrepos that behave this way.