I'm not 100% sure but I suspect the core is still trying to perform the original export all that your request and is having problem.

Try rebooting the MC200 as well.

861v6+ID40, HD621, 8000.2, 7200HC, 7200.2, SKYQ Silver, PS3, PDP-LX6090, QNAP TS870-Pro (8*6TB), Roon, iPadAir2.
[In Reserve] C15, MD600 (2*3TB), TwinStore RM (2*2TB)