I have added this note in case it helps others with the same issue.

Note that lines 8 & 9 below are the solution to the problem:

1. I am using Draftsight Professional 2026 SP1.
2. I found that Esnaps suddenly stopped working.
3. I discovered the problem was a corrupted user profile.
4. I tested this by renaming the old profile (C:\\Users\\[myname]\\AppData\\Roaming\\DraftSight) to DraftSight_old and re-starting DraftSight.
5. This cured the Esnaps problem, but it meant I lost all my customisations.
6. I reversed this step by deleting the new profile and renaming my original profile from DraftSight_old back to DraftSight.
7. I re-started DrafSight and all my customisations returned to normal, but so did the Esnaps bug.
8. I then ran the "Migration" command in DraftSight. This forces DraftSight to ask to migrate profiles from a previous upgrade when it is next launched.
9. I restarted draftSight, imported profiles from a previous install (2026 SP0). The Esnaps bug is cured and all my customisations are working.