server does not release file after streaming has ended

i have noticed this a couple of times:
after viewing last episode of a series I try to either move or delete the series episodes and folder.

I get a file in use error in windows on the server PC . which persists after waiting 5 - 10 minutes and retrying. - and after exiting the client on tablet and putting tablet into standby

I have to stop the server in order to complete the file operation, then restart it.

is it bugged or is it simply on a long timeout - if so how long ?

i was able to query the program that was holding the last watched video file, did not write it down but it was a long name, something like serviioservice.exe. windows 10

anyone ?

i finished a show yesterday via serviio . waiting 4 hours before trying to move it's folder on the server out of the serviio monitored folder & into an archive - still got " cannot move - file/folder in use" ?
going to the serviio panel, stopping the server, waiting a bit, then deleting or moving..., then restarting the server .. seems to work as a workaround. but why is there no auto release. is it a glitch with my W10 PC server or a bug , or is the serviigo app on my tablet to blame for keeping some sort of lock active ?