Applications /Utilities/ Disk Utility/ External Hard drive and check it is mounted. Please.
Also Nibbles asked about what you updated, can you offer some information about this update please.
I have also noticed you have Movies and shows in one Library. By shows do you mean Tv shows? That is not good, read the following support articles and check you have naming and file structure correct. You will need to fix your library link to the storage location if you have a mixed Content Type.
It’s my understanding that’s not a Library. That section is for Plex’s Online Media Sources enabled in Settings and pinned to the start menu. It’s the ad supported, streaming items. And it appears to be offline or unavailable or disabled (the yellow exclamation mark).
The two libraries containing the user’s personal videos are called Lexar Movies and Lexar TV Shows