With "Automatically cluster all new files" enabled, the files that could not be placed are clustered by Tagger._file_loaded when the last pending file has been handled.

That function returns early for a file that failed to load, one found unsupported, or one removed while loading, before reaching the clustering step. If such a file happens to be the last one to finish, the other files of the batch are not clustered. Loads finish in any order, so the same folder can be clustered on one run and not on the next.

To reproduce: enable "Automatically cluster all new files", add a folder containing several valid files and one damaged file, repeat a few times. Sometimes the valid files are not clustered.

Also: a file that was placed and then removed while the other files still load should not be put back into a cluster by that step.

Expected: the clustering step runs once the last file has been handled, whatever became of it, and ignores files removed meanwhile.