Be careful when dealing with OP, I highly suspect he/she use an illegal way to buy the courses and may result your account could get banned.
Review:OP gave me a vouch copy as I've asked for it and I got the course as GIFT by email.
When I received the gift by email, I unwrapped it, then activated it, and enrolled in the course... Up to this part, everything was alright. I got the course...
But about 15 mins later the course is gone. When I checked my courses section, the course was not available there.
Later I visited the sale page of the course I wanted and seen that Udemy is asking me to buy the course.
When I informed the seller about the issue, the seller sent the course again as a GIFT even when I've asked him not to send.
Because I don't want to risk my account by trying for the second time, as Udemy has already removed the course from my account...
Trying to log in to continue my course, unfortunately, my account got banned.
Your account has been suspended temporarily. Please reach out to
policy@udemy.com for assistance.
I don't know exactly how could this happen, but I think the vouch has something to do with this. Luckily that is a brand new account created to only trying OP vouched.
I suggest staying away to get vouching nor buy any course from OP until OP make a further explanation about it. I suggest take my and @akimit issue into consideration, and wait for @shasan further update, let's see if he/she has the same problem.