Lato Italics Takes Over Computer

I am trying to help a client who uses the Lato font in her marketing materials. Files are stored in Box and the marketing emails created and sent from CVENT. Their chosen font for branding is Lato.

For reasons unknown, her marketing email messages in HTML appear in Lato italics. Recipients see the message it as intended, not italicized.

This also impact Excel spreadsheets - any content in Lato is italicized.

The Box Drive app login dialogue box is italicized.

Sometimes the Box drive dialogue box looks normal, but if she copy/pastes the content of the dialogue box to Word, it will change it to Lago italics.

When she signs in to CVENT the dialogue box is italicized, as well.

This happens when using either Chrome or Safari.

She worked with Apple support. The removed all externally downloaded fonts using the Font Reset option and it did not help.

I created a new profile on her Mac and it looked good at first, but as she opened files from Box, the files looked good, then changed to italics. Same for the Box drive app.

I gave her a loaner Mac to use while I re-installed the OS hoping it would get rid of the problem. The loaner Mac developed the problem as well, and the freshly imaged Mac also repeated the same unwanted behavior.

What in the world is going on here?

TIA!