Have you charged your MBP from a fully discharged state using the WD19TB? Were you able to do this AND use the MBP for any decently heavy computing task? I have a CalDigit USB-C Pro Dock with an 85W power adapter and it croaks if I'm charging the 16" MBP.
No. I had my 16" MBP for just a few days and haven't done any pressure testing intentionally. Apple's official charger delivers only 94W in my use and I'm happy with the WD19TB delivering 90W. CalDigit claims no problem in using their current 85W TS3+ or USB-C Pro Dock with the 16" MBP, which may be a bit loose (there is reason Apple increases the power for the 16"). So from 94W down, there is probably chance of battery drain (see e.g. #292). But the chance should still be quite slim at 85W, from CalDigit's test/claim and my own experience (limited). I hope this helps.