/data/xAPI/statements with activity filter not working

[torinfo]

What version were you using?

Open Source version Release v6.4.0

What steps can we follow to reproduce the behaviour?

There are statements with activity id https://xot.futureteacher.eu/288/Future_Teacher_Thermometer/Online_cursussen_ontwikkelen in Learning locker, but wehn trying to retrieve them using the data/xAPI/statements endpoint, no statements are returned.

To reproduce, try to retireve statements with curl with a known activity id

curl --user key:secret -H 'X-Experience-API-Version: 1.0.0' 'https://lrs.dlearning.nl/data/xAPI/statements?format=exact&activity=https://xot.futureteacher.eu/288/Future_Teacher_Thermometer/Online_cursussen_ontwikkelen'

It doensn't help to urlencode the activity.

What is the actual behaviour?

If applicable, add screenshots to help explain your problem.

The above curl statement returns {"more":"","statements":[]}

What is the expected behavior?

I would have expected at least 1 statement, the one indicated in the screenshot.

Is there any additional information that will help us replicate/understand the problem?