Wikibase returns empty query (probably CirrusSearch issue)

Hellou, the frontend dev still has issues querying our data. Here the details:

[…] I can't seem to filter the results by a certain property, e.g. we want to filter all the results for only entities that have the type set to Module. e.g. P1426 = https://github.com/OPEN-NEXT/OKH-LOSH/raw/master/OKH-LOSH.ttl#Module

https://losh.ose-germany.de/w/api.php?action=query&list=search&srsearch=_+haswbstatement%3AP1426%3Dhttps%3A%2F%2Fgithub.com%2FOPEN-NEXT%2FOKH-LOSH%2Fraw%2Fmaster%2FOKH-LOSH.ttl%23Module&format=json&srnamespace=120&srlimit=10&sroffset=0&origin=_

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It looks like WikibaseCirrusSearch isn’t set up properly on that wiki (no results for haswbstatement:*) – in fact, according to siteinfo+extensions (Special:Version isn’t visible for some reason?), the extension isn’t even installed.

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May be related to #97 (closed)

Please let me know if WMDE can help troubleshooting this. I'd immediately contact them (but I'd need specific requests) :)

THANKS!