File > Auto Import > Auto Import Settings forgets the previous setting of Add To Collection and always displays it unchecked, even when it was previously checked.
Tested on LR 12.1 / Mac OS 12.6.1.
To reproduce:
1.Do File > Auto Import > Auto Import Settings.
2. Check Enable Auto Import and Add To Collection, selecting an existing collection.
3. Verify Auto Import works by dragging a photo into the watched folder.
4. Do File > Auto Import > Auto Import Settings and observe that Add To Collection is unchecked (bug).
This bug has been around since time immemorial, but the original bug report appears to have gotten lost. See these threads for relatively recent reports of the issue:
https://community.adobe.com/t5/lightroom-classic-discussions/problem-auto-import-to-a-collection/m-p...
https://community.adobe.com/t5/lightroom-classic-discussions/auto-import-s-quot-add-to-collection/m-...
https://community.adobe.com/t5/lightroom-classic-discussions/collection-in-autoimport/td-p/13563934