Yes it is, and I have not been able to repeat it. Once I removed the reference to the datamodule, the Object Inspector's drop-down was populated. When I put it back again, it remained populated.
I'd be left with doubting what I saw except that I saw it repeatedly before posting here, restarting the IDE, doing full compiles, with the data module in either uses clause all the while. Then I removed the reference to the dm and all became well, and stayed well after I put it back again.
I don't blame you for wanting to know what I'm smoking.