If I try to burn an MPEG2 Program Stream file to DVD+RW, it proceeds normally in the Writing popup until it gets to "99% completed", then hangs.The access LED on the front of the DVD writer keeps flashing, as though there's activity of some sort on the writer.
If I click on Stop, then Abort, it then hangs in the Aborting... popup, continuing to show "99% completed". Clicking on the rec "close icon for the popup window has no effect. Choosing "Quit" from the popup menu for Toast in the Dock has no effect. Quit on Toast in Activity Monitor has no effect, either. Force Quit in Activity Monitor causes Toast to quit, but the access LED on the writer keeps flashing.
Restarting the Mac stops the access LED from flashing, and when the Mac has restarted, the DVD is mounted with the name I gave it, but its top level directory is empty: it doesn't have the expected top-level VIDEO_TS directory. The DVD can be erased by Toast, and the same DVD can be written to as a data DVD by Toast.
MacBook Pro (13" 2019, Four Thunderbolt 3 ports)
LG SuperMulti Blade GP70NS50 DVD writer
macOS Catalina 10.15.3 (19D76)
Toast Titanium 18.2.1 (5887)
Verbatim 4.7GB DVD+RW