100% go with a different ANT+ dongle. There’ve been reports of glitchy behaviour from discount dongles.
Garmin is always a good bet. Suunto are fine too. Realizing those are expensive brand new, you can find them on the used market, or even at thrift stores bundled with older fitness trackers. (look for new-old-stock Garmin Vivofit trackers) Of course, that assumes the luxury of time so you might have to spring for new if you want it fast.
In the meantime, you could try refreshing your ANT+ drivers if you’re using a Windows PC.
EDIT - further to what @Paul_Southworth mentions below, I’ve had good luck with Coospo electronics, though I can’t comment on their ANT+ dongle specifically.