Filter rules keeps giving me an invalid message

[HansB]

Hi,

When making some filters with an OR - function recently I keep getting an "invalid" message. When I created it, everything looked fine, I could save it, I could create it.

But when I want to adjust, change or include a new rule i get the message below. (apologies my example is in dutch). That my rules are invalid. Nothing has changed in the data sources, nothing has changed in the labels,...  I just pressed the pencil to open the filter and make the change.

I do think it still functions in the background, not entirely sure, but i just can't change it. I have to remake the filter all over.

Is this a general bug? Or is it something I am using in a wrong way?

Much appreciate the responses in advance