"THANK YOU" Apple ...
UPDATE : FIXED by MacOS 10.13.6 https://support.apple.com/de-de/HT208864
Since High Sierra (proved with any minor releases up to 10.13.2) the photos app doesn't allow to import AVCHD videos (known from Camcorders like the one from JVC) anymore from external devices.
Indifferent if AVCHD store is attached by USB MassStorage (USB cable to Camera) or SD Card in Macbook Pro or USB Stick.
This has also been verified as a drawback by support Ticket 100406334459
There is a VERY LIMITED known "workaround":
Copy complete Camera Storage Content to local disc (hard drive); then use Photos > import ... dialog and point to the directory.
Unfortunatly there are many drawbacks that makes this unusable:
1. any record dates are thrown away.. all Videos imported from Copy are Timelined by "TODAY" instead of it's recording date.
2. disc space is limited!!!
(unfortunately I wasn't able to add the last point due to Text input size limitation):
3. Video duplication is broken, on each copy, already imported videos are not known to be already imported but are suggested to import again
and yes: "Image Capture" (the core app behind) doesn't list the videos anymore too
++ another "feedback"
The import of Videos in AVCHD Storage is no longer available as described on https://support.apple.com/de-de/guide/photos/phtae4e05c67
Worked flawlessly up to OSX 10.12, in 10.13 no videos are listed anymore