StatsStan or CmdStan files cannot be found

I have StataScan and CmdScan running, and a model solves just fine. The problem is when I try to literally re-run the same model or make a minor change and run again. I get a cryptic message like this:

file C:\Users<myname>\AppData\local\Temp\ST_ec_000001.tmp not found

This is right after being told:

StataScan version: 1.2.3
CmdStan version: 2.16.0

I appreciate that this is a cryptic file name. But the only way I seem to be able to run again is to delete the c:\cmdstan* directory, re-install, and make the EXE again. I also appreciate that this is a newbie question, and that StataStan is doing a lot of “under the hood” work to interface with Windows, but there must be something wrong with how I have installed CmdStan, I would guess. And it is seems to be absorbing a lot of time, several days in fact, to get this interface to work; that is a great pity, of course, since it is obvious that it is a valuable complement to the existing Stata bayesmh commands of version 15.

Any clues on the source of this error?

Operating System: Windows 10
Interface Version: StataStan and CmdStan
Compiler/Toolkit: Rtools