Yoast recently changed their tracker Universal Analytics function from the Google recommended ga() to the more obscure __gaTracker(). We suspect it was to reduce conflicts.
But because they failed to notify anyone of the change and it didn’t make an appearance in the changelog, it’s had the side effect of stuffing up everyone’s event tracking (see their forum for complaints).
We are working on a big release to Google Click Tracking (soon to be released v1.3) which has a host of other fixes and features. We will aim to put in a workaround to detect the change in tracking function and ensure it’s working correctly with their plugin (since it’s the most popular of its kind).
The workaround in the meantime is to use the Custom Code box on the Advanced Tab under Analytics->Settings and insert the following code which will restore harmony with the ga() tracking function:
var ga = __gaTracker;
If you are still having issues tracking events with the GCT add-on for ThirstyAffiliates, please contact support.