"The feature could not be split. Field is not editable"

I get this error message when trying to split a simple (non-network) line feature using the ArcMap split tool. The class is in a File Geodatabase that happens to have a GlobalID assigned.

Searching through previous posts it's seemed that folks have seen this error when there have, for one reason or another, come to be two length fields present on the class. I've checked my class multiple times and there's only one length field -- named Shape_Length.

Being curious about the GloabalID field I copied the class to another, excluding the GlobalID -- and found that I can split lines in the new class. Which raises the question -- is there something about having a GlobalID on a feature class that would prevent the split from working? Or did something else shake loose by copying the class?

I'll keep digging into this, but if anyone has had a similar experience any insights would be much appreciated.

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An additional point of information about this database is that it had been compressed -- at which point no editing was possible -- but I un-compressed it, which allowed editing. Other edits in the database, and on the line class with the GlobalID (except for split) work fine.

Thank you,
Ed