Problems enabling additional files in large, partially-completed torrents, again

[ferdnyc]

I'm once again seeing issues when a large-scale (thousands of files) torrent is Seeding in a partially-completed state, and additional files are then enabled for download in its "Files" tab.

What's happening now (different from #3218) is, when new files are checked in the torrent's Files tab, the torrent goes from Seeding to Stopped, and can't be started again until it's manually Force Re-checked. (Without the Force Re-check, attempts to "Queue" instantly reset to Stopped state; nothing additional gets downloaded.)

I've seen this happen several times now, enough that it's risen from "weirdness" to "reportable pattern".

I'll try to reproduce in a more controlled manner and capture logging, but I have to wait for the torrent in question to finish its post-completion low-resource Checking run first, following the downloads that precipitated the most recent occurrence... which, due to the size of the torrent (1788 files in 37,194 pieces totaling > 40 GB) takes somewhere between 20 minutes and an hour each time.

(While I'm currently seeing this issue with the version below, I think it may have started sliiiiightly before this particular beta build, though "probably" not more than 2 or 3 weeks ago. Rough guesstimate.)

System block

Java 11.0.24 (64 bit) Red Hat, Inc. /usr/lib/jvm/java-11-openjdk-11.0.24.0.8-2.fc40.x86_64

SWT v4956r12, gtk/3.24.43, zoom=100, dpi=96 Linux v6.10.12-200.fc40.x86_64, amd64 (64 bit) B3.7.0.1_B02/4 az3 en