'open in new tab' keyboard modifier not working on Mac OS

[MC Hammer]

This issue has been raised by one of the developers I work with, and who uses a Mac (and Chrome/Safari).
We mainly produce HTML 5 help and sometimes link to specific bookmarks, i.e. in topic A, there is a link to a bookmark within topic B (not just a link to topic B).
By default such links open the target topic at the targeted bookmark in the same tab.

If, in Windows, I want to open such links in a new tab, I can either right-click them and select Open link in new tab, or use keyboard shortcuts (CTRL + middle mouse button click). However, my colleague is saying that if he uses the equivalent Mac keyboard modifier ("command click"), such links still open in the same tab (at the targeted bookmark). Right-clicking to open links in a new tab on Mac OS works fine, so this seems to be specific to the keyboard modifier.

See https://help.semmle.com/lgtm-enterprise ... oject.html
If he uses the keyboard modifier on the About LGTM link (link to a bookmark within the target topic), the linked page opens at the targeted bookmark, but in the same tab.
If he does the same on the neighboring link called plugin to download alerts (link from topic to topic), the linked page opens in a new tab.
In Windows (Chrome and Microsoft Edge), both linked topics open in a new tab when I use CTRL+middle mouse button click.

Has someone noticed this too, and is there a way to fix this? Not sure whether this is related to something Flare does or not, but just thought I'd ask here in case someone has come across this before.
Thanks in advance.