What could be the cause of Video Security Client App being stuck on ‘seeking’ when trying to playback older video?
If the VSC App is installed on the onsite user's computer, then the cameras most probably are added to VSC one by one. In this case, when you are trying to playback, this is camera replay and not VRM replay.
The camera can replay only the last 32 recorded blocks.
If you want to be able to replay the recording for the complete retention time, you should use VRM replay. VRM should be accessible and added to the VSC.
Nice to know
An alternative way to playback older videos is Operator Client installed on your workstation. Check this article and see how you can show the recorded video via BVMS Operator Client.