Add to Queue just doesn't work

I'm not sure if it is the sheer size of my vault, although other people have way bigger ones than me, as I have a few thousand items.

But when I try to add something to a queue, it just doesn't work.

Start by reproducing the failure when using Add to Queue in a vault containing a few thousand items, then trace the queue-add entry point and any related diagnostics. The issue provides no file or test location; done means identifying the failure cause and confirming that an item can be added to a queue in a large vault.

Written by the indexing model from the issue text.