I'm having the same problem with mine. I tried what you suggested and it will charge with the cord now, but only by doing this method. I think we pay way to much for these phones to have them act and work like this! I went out and bought a wireless charger before I read the comments. That makes me even more upset. I Hope they call a recall on this issue soon. Looks like a lot of people are have this issue.
this is what i did by a freak chance and it seems to be working in the mean time.
1. plug in your s8 to the charger (you will be notified that there is moisture detected)
2. restart your s8 (make sure not to remove the charging cable)
3. make sure it shows how long until full charge.
4. You have by successfully by passed the moisture error.
Yes this is what i did too! Do you know whats causing this problem?
I was out yesterday and noticed the notification for moisture detected ive not slept all night trying to figure out how to dry my less than 30 day old phone. I went out and bought damp rid AND rice and threw all of it in a bag woke up at 4 am trolling the internet and see this . I turned it off plugged it up got the notification again turned it on and its charging but it says use the charger it came with ummm hello i was lol even the extra port thingys said the same so once it charges ill see how it goes but this worked for now im calling them when thet open and it's on