I hope the below information will help you to clarify the maintenance mode query.
Issue Definition:- Query about maintenance mode in SCOM and SCVMM
SCVMM is removing the Host from Maintenance in SCOM in every 6 hours. This happens when we put the host in maintenance from SCOM directly and not from SCVMM. We check about this behavior with PG and understood it is by design and the suggestion is to put host in maintenance from SCVMM as the fabric needs to be managed from SCVMM. And if you put the host in MM in SCVMM, it will be automatically in MM mode in SCOM for 1 yr. MM integration functionality only works from VMM to SCOM but not in vice versa.
To avoid SCVMM to remove host from maintenance, we have the following options.
1) Use SCVMM to add/remove Hyper-V hosts in/from maintenance.
2) In case you need to put the host in maintenance from SCOM, remove the maintenance integration option from SCVMM. This will make sure that the SCVMM job will not remove the Hyper-V host from maintenance. In this case the hosts will not be added to maintenance in SCOM when you put the host in maintenance from SCVMM.