>>I don't think DoEvents and AutoYield are relevant for DLL.
>
>Communications via COM depend on parts of Windows that are outside of VFP. If VFP is blocking processing of Windows events, it might interfere with that.
>
>Testing of these is easy, literally one line of code each.

Seems like it made no difference. I added DOEVENTS following with
_VFP.AutoYield = .f.

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I'm closing for now, will resume Saturday night.