New mapping in Base contract - Openzeppelin upgrades

I am trying to add new mapping to base contract and when I upgrade using "upgradeProxy" I am getting below error , "New variables should be placed after all existing inherited variables".

Using " uint256[1000] private ______gap;" in Base contract. Help me to understand the issue and to solve the same.

This upgrades plugins do not properly detect gaps yet, but this is being worked on. Subscribe to for updates.

If you are sure that your storage layout is safe and that you are using the gap correctly, see this comment to disable the error.