If something works in Dev and doesn't work in Beta then you can't do anything but wait for the next update. the same applies to Dev and Canary. because at the top sits Canary and if something is fixed in that channel then eventually all other channels below it will receive the fix too based on their update cycle. for Dev is 7 days and for Beta is 42 days.
Yeah, it's as the HotCake said. It's like a flow of command that starts with Canary and works it way to Beta. Dev only being updated about once a week, and Beta about once every six weeks. So some features you might find in Canary might take a week or more (updated or two) to catch up to Dev if it's chosen to move on, and what came out of Canary to Dev might take six weeks to finally reach Beta from Dev. I would encourage you to download Canary and use it alongside of Dev to get the most of everything. If you haven't already downloaded it. It's stable even for the most beta stage of the browser. I have almost no problems with it except a page crash now and again which is usually promptly fixed, and if any glitches or bugs or crashing do comes up it's usually corrected within 24 hours (or less) being Canary updates everyday and in your case you can hop back to Dev for that time period. With your issue stick with Dev or Canary right now into those features you're looking for catch up to Beta.