This may be alarmist, but I can't see any explanation other than that there's a bug in FileMaker Pro 15 Advanced's script editor (possibly associated with the introduction of the Undo feature).
Yesterday, I created a script on a client's live system. I tested and debugged it fully, and signed off on it.
Today, when I go into that system, the script has reverted to a very early version, 25 lines or so, with code that I had actually eliminated in the final, which was probably 80 lines. There is no sign of the final version anywhere in the system. It's gone.
It was a script to consolidate two duplicate records into one. I tested this script on a couple of records. When I search for them, they are fully consolidated – a process that could only have occurred using that final version of the script.
So the script was definitely there, and finalized; those consolidated records serve as evidence that it was, otherwise, how were they successfully consolidated?
(And no, I'm certain I didn't accidentally "undo" the work I did – which would have required me to execute about 55 consecutive undo operations.)
Anyone with a similar experience?