This adapter works as intended, but it is not powerful enough to charge the 13" 2018 mbp when connected to the thunderbolt display.
That means that if you use a really hungry app for hours, your battery will slowly loose its charge until the macbook shuts down.
It's worse if you use you macbook display at full brightness.
On the good side, it does charge the macbook when you don't use a powerful app with the brightness at an acceptable level.
I use I to charge my new Mac Book Pro from my Thunderbolt monitor. Works great! Took about 3 weeks to come.
Arrived almost one month after ordering which is unacceptable in this day and age. Web chat is prompt however and always responsive. Pleased with product.
on a 15in macbook pro, Apple's system report -> power shows:
AC Charger Information:
Wattage (W): 40
connecting via the thunderbolt display.