The UFC are reportedly frustrated with Conor McGregor's lack of promotion for his lightweight title fight with Khabib Nurmagomedov.

McGregor will return to the octagon for the first time in nearly two years when he takes on his heated rival at UFC 229 in Las Vegas on Oct. 6, in what is being billed as the biggest fight in MMA history.

The fight is expected to break the current pay-per-view record of 1.6 million buys set by McGregor when he faced Nate Diaz at UFC 202 in 2016, while tickets notably sold out in just three minutes, already becoming the second largest gate in UFC history in the process.

Curiously though, there is yet to be a press conference for the event. When McGregor was headlining UFC 205 in Nov. 2016, there were two press conferences for the event, with the first one being as early as late September. But in this case, there is barely any promotion over the event.

According to Dave Meltzer of the Wrestling Observer Newsletter (transcribed by Uproxx), it is because the Irishman simply hasn't "agreed to do anything" and while the UFC are frustrated with him, McGregor holds too much power to be given any form of punishment.

"One of the reasons you haven’t seen much in the way of interviews and such is that McGregor has not agreed to do anything. There are no press conferences scheduled because McGregor at this point hasn’t agreed to them. There is a lot of frustration within the UFC about McGregor’s attitude, but in the end, he’s got the leverage and the ticket sales and secondary market results only give him more leverage. The feeling is that this may be the biggest non-boxing PPV of all-time, and the only reason it wouldn’t be is that McGregor hasn’t been pushing it hard. McGregor was able to get a larger piece of the action for this fight than any of his UFC fights to date, so there is a direct correlation more than ever between his work in promoting the fight and his pocket book, but this may also show that he knows he’s in a real fight and doesn’t want to break training."

McGregor could be training hard for the Nurmagomedov fight. The 29-year-old is taking part in a training camp in Dublin and according to reports, he will not be arriving in Las Vegas until mid or late September.

Other than a little back-and-forth with Floyd Mayweather, the former two-weight champion has also been posting pictures of him training on social media recently.

However, it's not the first time McGregor dodged his promotional duties. His rematch with Diaz was initially supposed to take place at the monumental UFC 200 event, but it was called off when he decided against flying over for a press conference.

He soon claimed he was retiring, sending the MMA world into a frenzy, before later delivering an explanation that he simply wanted to focus on training instead of promoting. Maybe that's what's going on in the buildup to the Nurmagomedov fight too.