Planner task comment encrypted

Hi guys,

We started to use Planner & tasks in Teams recently. However, I noticed that the comments we left in tasks are all encrypted. 

Later, I realized that this was caused by the encryption settings in Exchange Online.

I disabled the OME transport rule. I can leave unencrypted comments under new tasks now which is good. But in the existing tasks, I can't leave any new comments (encrypted or unencrypted).

Is this expected? Anyone has the same behavior with me?

Any help would be really appreciated!