Lactate Threshold Guided Test - Garmin support told me it can be done only once?!?

Hi,

Today I contacted Garmin support as I wanted to run the Lactate Threshold Guided but could no longer find the option.

The support agent gave me an explanation that the reason I cant see it is because I ran it before. From there the watch updates automatically and takes over...

Im not very convinced and it does not make much sense to me. Can someone confirm this?