I just wanted to add my two cents to this topic in case someone else runs into the same issue I did.
I was obviously searching for a reason why my popups in portal weren't working in Chrome and came across this topic. I didn't really pay mind to the zoom settings at first, I never zoom in on a webpage so I didn't think this applied to me.
Looking at my display settings on my laptop though I discovered that the default setting is zoomed to 125%. That is the recommended setting. Changing that to 100% fixed the issue.
I know Robert mentioned resetting things to default settings but in this case, the default setting would be 125% because that is tagged as the recommended setting. So just something to keep in mind.