Wondering if I should be able to profile an app built in an eariler version of Unity using the memory profiler?
This doesn’t seem to be the case. The “Capturing snapshot” never completes, and progress bar just hangs at 100% without any warnings or errors 
Just to be clear, I’m profiling from Unity 2018.3 on a app built from 2018.1
This is sadly not possible. The new back-end used by the new Memory Profiler package was finalized in 2018.3 and the package is not compatible with the old back-end used by the BitBucket Memory Profiler and @Peter77 's Heap Explorer . However, the Import button in the new Memory Profiler package allows you to import snapshots taken with the old back-end so you can e.g. take a snapshot with the BitBucket profiler (our import conversion currently has no implementation for Heap Explorer’s file format) and import it.
Oh yeah and, the old back-end is sadly a bit prone to crashing… We don’t back-port changes to 2018.1 (Tech stream) anymore though.
Ok, thanks for the info