Thumbnail folder showing in manual import

Sonarr version (exact version): 3.0.3.899
Mono version (if Sonarr is not running on Windows): 6.8.0.105
OS: QNAP QTS 4.4.3.1354
Debug logs: https://drive.google.com/file/d/1RPeZm2dUCljrWfUMytq4Dgk-VYxPKDva/view?usp=sharing
Description of issue:
When I run a Manual import for One piece Anime which contains huge number of files, I found a thumbnail subfolder named .@_thumb which shows items in the thumbnail folder presented in the list.

With a large number of video files, the number of thumbnails create extra workload and extend the list unnecessarily.

This issue is showing in every folder I Manual import. and it makes manual import process no painful and takes lot of times.

As well can’t you make an update with an option like once I do manual import for one season it won’t show again when I do the manual import of the next season. it will safe time and help to finish the importing more faster with no extra load