As the question states I have a Custom Field, called Priority (it seem to be a feature available so I just used it) but now I have a little challenge in using it further.
The Custom Field appears on cards like this:

Now when I go to my Workspace and want to search multiple boards and filter by this 'Custom Field, Priority: High it does not work, why?

The annoying thing is that I did a search on one board and it works, I really don't understand this.

I am hoping and sure that there are a lot more knowledgable folk in our community than I that could resolve this so I'm really hoping to hear back from someone asap.
Many thanks in advance :-)
Kind regards
David.
PS: I found a very good link on the Trello Support page that details the special operators but I could not find a solution there.
https://support.atlassian.com/trello/docs/searching-for-cards-all-boards/