I found another issue, when click [tab] on snippet tabstop wouldn't move to next tabstop instead trigger emmet expand (if emmet.triggerExpansionOnTab on).

Is this same problem?

@t7yang does that issue still occur for you on the latest Insiders? I'm unable to reproduce it. If it does, can you paste an example abbreviation for me to use?

@rzhao271 No, fixed now.

@rzhao271 I am unable to repro this issue. I tried to do an explicit Emmet: expand abbreviation and it worked fine for me. Can you please confirm ?
I did the exact steps as u have mentioned in the bug description

Oops!! I missed the first step in the repro - Have emmet.triggerExpansionOnTab set to true.
I can repro it now and what I also oberved is when this setting is false( which is by default) and if we explicitly run the command Emmet: Expand Abbreviation, the expansion works fine.
Looking into the issue

I found this piece of code in abbreviationAction.ts, inside the function expandEmmetAbbreviation() -

// When tabbed on a non empty selection, do not treat it as an emmet abbreviation, and fallback to tab instead
	if (vscode.workspace.getConfiguration('emmet')['triggerExpansionOnTab'] === true && editor.selections.find(x => !x.isEmpty)) {
		return fallbackTab();
	}

Seems like when the setting triggerExpansionOnTab is turned On, and we have a non-empty selection, we fallback to default Tab behavior

@rzhao271 can you please help me understand why we have this check in place, as I am uanble to comprehend any scenario that needs this.
I also verified that if we remove this code piece, we get the right behavior

Thanks for the update!
It seems Ramya added in that exact part of the code over 3 years ago but didn't link it to an issue: 78809b7
I'll change this issue to a Backlog Candidate feature. That way, we can see whether the community wants to enable Emmet tab expansions on selections.

This feature request is now a candidate for our backlog. The community has 60 days to upvote the issue. If it receives 20 upvotes we will move it to our backlog. If not, we will close it. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

Thanks @rzhao271 . My only concern here is that for cases where we have emmet.triggerExpansionOnTab === false (which is by default), we can still expand the selection by explicitly running the command Emmet: Expand Abbreviation.
So , I don't see much utility of the above mentioned check.
Please let me know if I am missing something here