Hi tscott,
Do you get the same result if you use Intl.DateTimeFormat().resolvedOptions().timeZone? A quick look at the documentation for Moment suggests that guess() first uses this command, and if it fails it attempts to guess by calculating the difference in offset. resolveOptions().timeZone works in over 90% of browsers, so unless you're targeting old browsers it should work fine.
If that still fails, try using moment.tz.guess(true) to clear its cache. Again, from the documentation:
"By default Moment Timezone caches the detected timezone. This means that subsequent calls to 

moment.tz.guess()

moment.tz.guess()

Thanks for your response bgooldfed!
Just to clarify, I would just need to swap out the single var timezone piece with either of those values, correct?

So either:
var timezone = Intl.DateTimeFormat().resolvedOptions().timeZone;
or
var timezone = moment.tz.guess(true);
Right?

That is correct :)

Thanks so much bgooldfed, the first option worked!

As a separate but related question, do you know of any other options to get the abbreviation to work? It seems like that condition is working to mixed results similar to how the timezone field was prior to the change:
Looks like this section should be doing that abbreviation, but I'm not sure where the issue is after looking at the documentation you sent.
    var date = new Date();
    var timestamp = date.getTime();
    var abbr = moment.tz.zone(timezone).abbr(timestamp);
At the end of the day it's not a huge deal since I can always just use branch logic in the survey flow to take care of it, but if JS can do it for me I won't complain

Glad you got it working!
That is very odd regarding the abbreviations, it should work fine how you have it... Are you able to confirm that the timestamp variable is working properly?
You could also try:
var abbr = moment.tz(timezone).format('z')
However that won't capture daylight savings time (because it only checks the general timezone, not the actual time of year).

bgooldfed I'm almost wondering if maybe Moment wasn't properly loaded into the survey since in testing, moment.tz.guess(true) didn't work. Taking a look at the JS in the very first question prior to the one that contains the code block in my first message, I can see the following:
{
/*Place your JavaScript here to run when the page loads*/

// Loading scripts to capture respondent's time zone
var loadedMoment = loadScript("https://momentjs.com/downloads/moment.min.js");
var loadedTimezone = loadScript("https://momentjs.com/downloads/moment-timezone-with-data-1970-2030.min.js");
   
  if (loadedMoment && loadedTimezone){
    waitForElement();
  }
Looking at the documentation it looks like this should be used instead? Just not sure how I would need to change the above to accommodate for that.

As always, thank you so much for your help! Really appreciate you taking the time to help me learn!

Try popping those script tags in the docs into the header of your survey. See point #5 on this Qualtrics article for some more info and a link to instructions.
That should let you call moment from anywhere in your survey.

Hello @bgooldfed  and @tscott , 

I’m attempting to use this JS to capture timezone in my Qualtrics survey, but I am unable to actual get any data populated. Could you provide more direction on how this is laid out in your survey flow? More specifically, is `timezone` and `timezone_abbrev` added to your survey flow via embedded data? In addition, is it at the front of the survey or located directly under the block where the text entry question is provided. Any information would help clarify as I am not getting the intended output; everything is blank in my data export. 

Hi @dkgreen!

is `timezone` and `timezone_abbrev` added to your survey flow via embedded data?

Been a while since I’ve looked at this, but yes it would have been.

is it at the front of the survey or located directly under the block where the text entry question is provided

Best practice would be to put at the front of the survey. Putting it there ensures it is accessible by all questions that come after it. (Placing it after the question that references it won’t work)

It might also be worth double checking whether moment is loaded in the survey header (see previous link and post) before testing everything.

Good luck!