So it technically depends on the extended release formulation, so from a layman's perspective, yes you should likely ask your doctor or even better ask a compounding pharmacist (as a general rule if you have questions about medication you're better off asking a pharmacist rather than a doctor.)

Given that...

From a technical perspective the only definition of extended release is a lag phase after ingestion. This means there's no immediately discernable difference between delayed release through anti-dissolution coating and slow dissolution through a hard-to-dissolve substance. (Even when you read something like two different pills saying delayed release vs extended release, there's no legal difference and the FDA doesn't give a fuck about the naming. This might be different in other countries so Americans benefit from other Country's health systems in naming. I'm not sure.)

Coating-type pill formulations should not be crushed.

Suspension-type formulations actually can be crushed to a certain degree. Typically humans aren't going at the pills like crazy in a mortar and pestle and don't have the strength to separate the suspension properly so it'll still have a slowed release effect. But yea if you smash them too hard then yea you can actually mess up the way that works.