Please wait, starting configuration wizard for toshiba_ac

I’m trying to add the integration for my Toshiba AC unit, but the “Please wait…” message just stays there and nothing happens.
Several months ago I was able to add it, but then for some reason it stopped working. Since then I have done a clean install, and found out the Toshiba AC integration was no longer available.
I recently found out that it is available again, but when I try to install it, I get the ‘please wait, starting config wizard…’ and it doesn’t go any further.

[edit] hmm, I just noticed it does this for any integration I try to add. Just tried to add my Shelly dimmer, does the same thing. Any suggestions other than a clean install again?