Hi,
I understand the filter function was reworked a bit in 9.0.0. But for me it seems that filtering in an album for images having a rating is not working correctly anymore.
I noticed this behaviour in 9.0.0 in a windows and linux environment.

I have an album with image mixed with no rating, 4 star and 5 star rating. For example I want to see only images that acutally have a rating, I open the filter sidebar and in properties I click on a star. The filter condition is set to "greater or equal". The expected behaviour should be to display all images that have a rating so my 4-star and 5-star images. Thats how it works before 9.0.0.
But now acutally nothing is happening. I can change the filter to two, three, four, five stars - nothing happens.
I still see all images, even the ones without rating at all. When I change the condition now to "equal", the filter is working and no image is displayed just as expected. 
When I now change back to "greater or equal", suddenly I see only the images having a rating. So now the filter is working... 

I hope this was somehow understandable. For me I can reproduce the behaviour on different systems regardless if the images had a rating or if gave them a new rating. The filter is not working.

Thanks for looking into this.