A Microsoft update KB4013429 March 14, 2017 created issues with the mpeg2 handling libraries. I do not think this is your issue, but some users (in the Encore forum) reported odd and inconsistent behaviors. So it is possible it has added to your woes. I did not see the problem till I tested it in response to reported problems. On one PC, every access of an mpeg file in Windows Explorer resulted in a "silent" crash (explorer just closed without opening the file) and same for Encore trying to import a file. On another PC with the same updates installed, I had no problems.
Some users struggled with removing updates, but this was fixed by a March 20 update, KB4015438.