I love Opus 12, and this is extreme nitpicking, but ....
I have had the following issues with Opus since version 10, it still happens in Opus 12.
a) Sometimes when I copy or move files from zip/rar archives into another folder using a dual lister, the information in the target list does not update. E.g. a folder remains listed as "empty" although there are now files in it, file sizes are listed as the old value, although they have been overwritten.
A similar problem occurs with non-refreshing of file listing details (file sizes still listed as old size after overwriting, new files not appearing, folder sizes still listed as the wrong size, etc.), almost always, when copying or moving between USB memory sticks, or from memorystick to/from HD.
As far as I see it, in 2016, I should NEVER have to "manually refresh". If for some reason I have to manually refresh, it should at least be happening in a consistent logical way, e.g. I should be able to know before the operation I attempt that "this one will require a manual refresh". For example, ALWAYS when copying to USB stick. But it seems to work inconsistently, sometimes it refreshes the list and sometimes it doesn't.
c) I cannot drag and drop files out of archives into other programs, like I can with normal files (why not extract to temporary ram-disk?)
d) When "copy-as" out of archives, it asks me for the new name for the first file, but sometimes Opus uses that new name for all the files, even overwriting (without confirmation), the original file with the second one that is extracted, etc.
I have not found exact ways to reproduce any of these frustrations, but they happen often enough during heavy use, I would say once every week or so I encounter one of these problems. Maybe some of the developers have encountered other reports of this, and maybe this vague explanation might help. I will update this thread as soon as I can reproduce some of these gripes consistently.