Another problem thrown up by VS 20206 18.6

[Perdrix]

For one of my projects, I am getting lots of errors like:

1>C:\Qt\6.10.0\msvc2022_64\include\QtCore\qtimezone.h(251,10): warning C4251: 'QTimeZone::d': 'QTimeZone::Data' needs to have dll-interface to be used by clients of 'QTimeZone'

but I can't see what's causing it. Only some of the source files won't compile, but they generate lots of those "needs to have dll-interface" errors.

Any suggestions of what I need to look for?
Thanks, David

[Bright Car]

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