USB Storage Devices

I've been using Win10 since the general release. This was an update install on a Win7 laptop.
Apart from a few issues (waking from sleep on scheduled tasks, lack of control on updates) I have a problem with external devices.
If I use several USB flash drives/harddrive I'm able to eject one or two but then I can't eject any others. When this happens I don't get the menu option to eject/safely remove the device through "explorer" and the drive doesn't appear in the "safely remove" icon on the task bar. I can still access the drive without issue just don't have any way to eject except to shutdown the laptop. If I reboot the laptop but leave the device attached the eject option reappears.
The laptop is fully patched and I can't work out what is happening and google hasn't revealed any similar problems except the normal "device is in use" message.
Any ideas?

Do the flash drives show up on "This PC". Since you can access them I suspect they do. Have you tried right clicking on their icon and using the eject option?

The problem is that when this occurs the drives appear in "This PC" and I can still read/write to them BUT there is no "eject" option until I reboot.

If you right click on the icons of the flash drives, and open properties, what do they show up as under the hardware tab.

OK - just been using an external drive, via powered usb hub, without issue - eject option showing. Plugged in a second drive - again eject option showing and accessed without issue. Plugged in a third drive and able to access it with eject option still showing. Ejected this third drive - no errors reported. Went to eject the other two and eject option doesn't show via "My PC" - safely remove hardware on task bar also isn't responding. Clicking on any of the drives that are showing (internal, CD and two external) and then hardware shows all four with the three hard drives showing correctly. Clicking on each of these drives shows them as USB and working correctly.

Quick update - just checked and 45 minutes after I posted the reply above the Eject function has returned for both of the two external drives that were attached. Safely ejected one and then the eject function disappeared for the other drive. This time after a couple of minutes the eject function returned for the final external drive. Can't see anything specific in event viewer to indicate what is happening. I have a feeling it is going to be difficult to identify/sort - didn't have this problem in Win7

This is a longshot, but try hitting the refresh button when you open This PC.

I'm using a Belkin powered 7 port USB hub to connect the drives to my eMachines E525 laptop via one of its two USB ports. The drives are main brand only, i.e. western digital, maxtor. The issue occurs irrespective of which ports I use on the hub or which drives are connected - so no obvious pattern.