Not sure whats going on, but when i added the show Alias Grace to my plex it didnt show up and isnt showing up as something to even view as a possibility to watch from another source through plex. I went to the website and it was listed there, but when i click on the 6 episode list it loads for a second and then says something to the extent of "nothing to see here’ like its a broken link. Any admin able to look into this please? And yes this isnt something to do with my labeling etc, Im not a plex noob-maybe a journeyman! 
Still, experience says, it quite likely is.
If a title is listed on https://watch.plex.tv/de/show/alias-grace then there is no reason why it should not be match-able on a personal Plex server.
Therefore, please show the folder structure and the file names you have used.
File pathing:
Alias Grace → Season 1 → files
This is the link to the 6 episodes and when I hit it it errors. The one u sent me in German however does work. Very strange. It seems like there is an error with the English site link. If u switch ur language to US English and click on it does it error for u also?
Created test files and it shows up fine:
I also tested the English watch.plex.tv site you linked and myself with searching it, and it shows up there as well:
The English version also shows as expected on my side.
Please follow the naming shown above by @veeejay
then perform the Plex dance with the whole show.
In general, you should always include the release year of S01E01 into the show folder name.
Figured it out guys thanks a ton. Im dumb, and u were right. The season wasnt included in each episode name. i thought since each episode was named ‘part 1’ etc that it would pick it up. appreciate the quick responses and ur time!!
Here is the officially supported file naming: https://support.plex.tv/articles/categories/your-media/
