No idea why this is happening, but that could be a reason of this issue... But I have been doing some tests, and I have found a way to get it work!!
Make the Transcode Folder visible on your PS4, then choose the " Video File Engine " (or whatever you want to have it called) -- For me, choosing this, any files is starting instantly, and the time of the video file appears again (which is make the possibility to fast forward or backward!! I will try to find out if there is a way to put on UMS the possibility to use the " Windows 10: Serviio runs for me...
Just to be clear, i can see all the folders on the cloud drive with both of my laptops on my home network.
remote access is a completely different problem that i do not want to address right now.
I recently purchased a 6 tb cloud drive and after a bunch of frustration I finally mapped the drive and copied videos for streaming over my network to my PS3's. I made a new folder and copied 3 tb of videos to the cloud drive (took about 8 days over the network, thanks WD for no usb 3.0 support).