MKV file data is missing in V.1803 (playback not affected)

Version 1803 doesn't show some file details for files with the MKV extension. Version 1709 did not have this problem.

Using codec h.264, if I use the MP4 container, I get all file details. But if I use MKV, some details are missing, including frame width, frame height, frame rate, data rate, total bitrate, and the thumbnail image.

This occurs whether I create the file new as MKV, or if I convert an MP4 to MKV (I use XMedia Recode, copying everything rather than converting). And if I convert MKV to MP4, the file data appears. That seems to narrow the problem to the file extension.

Video playback is not affected in VLC or Pot Player. The problem lies strictly in the file details that Windows displays, and it's the same in File Manager and FreeCommander, so it appears to be rooted somewhere in Windows itself with the 1803 update.

Internet searches turn up the same or similar problem in Windows 10 as far back as 2016, but this is the first time I've come upon it. Any help would be appreciated.

It's both: details pane and rt click, properties, details.

File Metadata looks intriguing. I'm on my phone at the moment, but I'll look into that when I get back to the PC later today.