lyx keeps resetting bibliography style to plain

[Neal Becker]

Using lyx-2.3.2 (fedora 30 linux).

I'm writing IEEE doc (conf.).  I set default bibtex style to ieeetr (or 
IEEEtr).  But if I export latex, it says
\bibliographystyle{plain}
and of course produces the wrong results.
Using plain old bibtex.