The file structure I used is
\Show name\Season\Show name - S0xe0x - Episode name.mp4
for example
\Bodyguard (2018)\Season 01\Bodyguard (2018) - S01E01 - Episode 1.mp4
The name in the show tag, and Plex displayed, was
Bodyguard: Series 1
(this is one example, there were many others)
I’ve edited all the tags which has resolved the problem. I didn’t have to do the Plex dance, just rescanning the library was enough. The LMA was below TheTVDB agent and enabled when I first ran into the problem, and the problem persisted even when adding the files to another server with LMA turned off. This particular show had the year in the folder name and episode name, but others with the same problem did not.
