I just added an integer field "Size" to my project, however seeing strangeness:
1. I cannot use this field to search issues (not a valid search)
2. Most issues don't show this field as an entry in the issue editor, so I cannot set it.
3. Sometimes the column appears in the issue list for "Size" but mostly it doesn't appear (this is after refreshing or changing some size value on an issue where it can be accessed).
I did add and remove this field a few times quickly so perhaps that has broken something. To sanity check I added a second new field and that one behaves strangely as well.