Custom attribute cannot be used as work item query filter

Hello,

I have created a new enumeration of priority values and set it as the type of a custom attribute with the name "Priority" and the id is "priority". The id was auto-assigned when I created the attribute.

I added an editor presentation for this attribute, saved the changes and synchronized all existing work items with this new attribute. It has been in use for some time now.

Now the problem is when I use this attribute as a condition in a work item query, I am not able to retrieve any results.

Further more, if I add this attribute to the result layout, save the query, close it then open it again, the custom "Priority" attribute in the result layout is being replaced by the built-in "Priority" attribute.

Anyone knows what is wrong? TIA