First of all thank you Mr. Kean_1 for editing my sloppy post. Many kind souls in internet!
I have tried what Rockstar helping team advised me to do (see above) with such confidence, and it does no change.
I feel kinda stupid that I somewhat believe that they could be right.
I am sure it is not my console problem (i recently purchased it and without issue with other games)
and I am sure that it is not a network problem (i am currently in korea, not the bad one, the land of super fast internet)
After writing this post, I am going to report the result as the rockstar guy indirectly asked me to do (i omitted the last part of the chat)
If I don't, I'm afraid that it would make them think that their solution actually works for at least few people (and raises that level of ego and confidence),
and I agree that more people reporting should help resolving this issue.