Since all the years that this thread was started, I also now experience the same problem.
I did notice that when for certain movie libraries (not all, weird enough) you could go to the 3 vertical dot menu and then go to Manage Library > and notice that there was a menu option once with the advice to upgrade the library matching:
Upgrade Library Matching?
This library is currently using a legacy agent to match items and fetch artwork and other metadata. There is a newer, faster, and more accurate agent available for this type of media. Would you like to upgrade this library now?
Note: Existing items in this library will not be affected until they are refreshed. You can refresh them individually or upgrade all existing items with “Refresh All Metadata”.
After I did this, I was able to match to at least the correct info and such, except for the poster. The picture of the movie stayed a random frame of it, instead of showing the proper poster.
What is also strange is that when I choose Fix Match (yes, not Match… any more, so something got matched) I can now choose for the correct title and I see the poster on the right, but the matching process still did not finish correctly. And it is taking too long anyway, like it is not able to work it out, if you know what I mean. To my experience the matching usually takes place in just a breeze.
For some titles Fix Match comes with a selection to choose from, with others it says “No matches found”.
To overcome the poster thing I dragged and dropped the artwork that I found, but to do this with that many titles that I recently added is a bit cumbersome.
Anyhow, I did not experience any matching problems so far for months (or years now?). This is my first experience with this problem and it looks like there is some programming work to be done. Better redo a few things here, the way things work with the matching is also a bit illogical and feels clunky. Thanks!