I can only share my experience and what the guidelines suggest. The spaces (between words in the name and around the dashes) are important. As are the folder paths. The matching logic can be forgiving with non-compliant names and paths; right up to the point where it isn’t.
I’m not saying that this is definitely your issue; however, the first part of determining why this isn’t working is making sure best known practices are followed. Then, when it fails, we know that there is something else going wrong and can investigate further.
If you’d like to try a scan and collect some logs, I’d be happy to look at them.
https://support.plex.tv/articles/201643703-reporting-issues-with-plex-media-server/?_ga=2.172535907.1373724445.1573835538-949007416.1553659010
And if you need a utility to help you get your naming/paths sorted out, check out Filebot:
