use the MPROP command and select a single fitting.

Go to the Manufacturing tab.

I believe your fitting has an Insul Spec assigned to it or it is set to "Off".

Set that to "Not Set"

Has to be done one at a time with the method above.

Alternatively you can run a script with the following code and select multiple objects:

item.insspec = "None"

Moving forward you may want to change that setting on the ITM's.