Multiple Select Custom Field -- bug or user error?

Your software
My Mautic version is: 2.15.2
My PHP version is: 7.1.33

Your problem
My problem is: I’m looking into setting up several multiple select and single select custom fields for my contacts to be filtered by in the future. I can generate new fields, but the options to pick from are always reduced to the top listing whenever I hit Apply.

I can re-create the options, shuffle them around, and when I hit apply, all but the top option are deleted and that top option is set as default.

Pretty sure this is a Mautic bug, but I wanted to check for user error before I report it.