SolidWorks 2024 SP5.0

I saved a STEP file to SLDPRT and converted to sheet metal. The mass was as-expected.

After inserting this part into an assembly I noticed the total mass was far too high.

I tracked it back to this part. When I re-opened it the mass was double what it was before.

There were two solid bodies in the cut list instead of one.

I looked at the convert to sheet metal feature and "Keep Body" is unchecked (I never use this, it is unchecked by default).

Then I clicked X to close the feature without changing anything.

Then suddenly the mass returned to the expected value and the second body disappeared from the cut list.

After many tests re-creating this bug, I found it doesn't matter how many times I go in and out of the sheet metal feature, 

or rebuild, or save, the part stays at the correct mass and only a single body.

The bug only occurs once the file is closed and re-opened. 

Then I have to go into the feature, change nothing, exit, and the part returns to how it should be

and does not randomly change again after this.

I found nothing about this in searches. So this is how to work around it. Also raised with the VAR to get a fix.