500 unexpected error - when accessing resource mailbox property through ECP

Dear Team,

We are on exchange 2013 CU8, We are able to login to ECP/OWA, able to open user/shared or some of resource mailbox property however few resource mailbox property unable to access through ECP  getting error "500 unexpected error" after 2/3min

Need to know is this could be the issue of permission due to unable to access the property through ECP because all these resource mailbox are in different OU.

Please suggest.

Regards

Satish D.