.kmz file imported with incorrect orientation/rotation

I have:
Windows 11
Google Earth Pro 7.3.6.10201, build date January 13, 2025.
Garmin Basecamp 4.7.5 (c) 2008 - 2023

I imported a .jpg file (scanned image of a paper map) into Google Earth Pro, rotated it by about 90 degrees and saved this overlay map as .kmz file.
When I import this .kmz file into Garmin BaseCamp, it's shown with incorrect orientation/rotation on its side.

A week ago I followed the same procedure (rotation was just by a few degrees) and this overlay map was displayed correctly.

How can I fix this error?