Hi @“MovieFan.Plex”
It´s really a bug!
On those two lastest updates (Version 1.5.1.3520 & 1.5.2.3557) there are 02 kind of strange behavior. I will explain:
1 - Sometimes when i open the Plex Web interface some of the artwork in my TV Series simply disapears! See:
I need to close Plex and then open again…sometimes more than once to get all fixed. This only happens in TV Series!
2 - Sometimes Plex don´t download metadata for certain TV episodes.
When it works 
When does not 
** Most commom when i try to update more than one episode **
I already try Plex dance but did not work. Sometimes it works when i do this procedure:
1 - Delete the TV Series from the library
2 - Optimize Database (wait 01 minute)
3 - Clean Bundles (wait 01 minute)
4 - Empty Trash (wait 01 minute)
5 - Add the TV Series in library
I already start my server from the scratch to see it will work… with no lucky
Attached my PMS log files.
I know you can analyse and see what is happening.
THX for any help!
Braz.
