Formula frame, after it's created, has `position` settings inaccessible for editing. You can open the frame settings dialog either via 'Object' path or 'Frame' path (see https://bugs.freedesktop.org/show_bug.cgi?id=88144), but in both cases `Position` settings block (bottom of the `Type` tab content) is grayed out. If dialog is open via 'Object' path, then `Size` block is also inaccessible for edit (grayed out). Because of that, https://bugs.freedesktop.org/show_bug.cgi?id=88139 cannot be trivially worked around. Replication: as described. Blank doc, one formula with anything in it.
This only happens, if you anchor As character. Closing as invalid.