Blu-ray subtitles become buggy if user seeks
Whenever I play a Blu-ray with subtitles, the subtitles work perfectly until the first time I click the scrub bar, at which point they become desynced by an inconsistent (but very noticeable) amount, and nothing will fix it except hitting the Blu Ray 'home' button and starting the program over.
I have confirmed that this bug happens on Windows in VLC 3.0.3 and vlc-4.0.0-20180830-0537-dev; according to this forum thread, it also occurs in 3.0.2 but did NOT occur in 3.0.1
Pausing/unpausing does not trigger (or resolve) this bug. (Not even when the pause is long enough for the disc to have spun down.)
"Seeking" to the start of a chapter by selecting it from an onscreen menu does not cause the bug, only clicking the scrub bar does. (I'm unable to test whether the next/previous navigation buttons have any impact; the disc that I'm testing with sends the user back to the root menu when they're used, since it's a TV series rather than a film.)
Anecdotally, the desync amount seems to be much greater for subtitles that are meant to be on screen for a longer time; short lines (which aren't on screen for long) remain almost correctly synchronized.
I haven't observed anything like this bug for non-disc MKV files with subtitles.