Muric dash off his line led to the Cherries equalising in the 87th minute at Portman Road, with the visitors going on to score a stoppage-time winner.
It follows on from the Kosovan international allowing Bryan Mbeumo's cross to beat him at the death in a 4-3 defeat at Brentford in October, and an error-strewn debut in a 4-1 loss at Man City back in August.
Ahead of Saturday's crunch clash at fellow bottom three side Wolves, McKenna was asked if the £8m summer signing from Burnley was still his No.1.
"We support all of our players," he said. "We know that mistakes are going to be made over the course of the season.
"We think that he's an extremely talented goalkeeper, I have to say. I think he's got attributes to his game that are top, top class. He's also very young for a goalkeeper and settling into a new club.
"There are areas of his game that he's working really, really hard on and we're fully engaged in that process with him.
"Obviously he was disappointed with Bournemouth's first goal on Saturday. With any goal that goes against you it's never just one thing though. There were a couple of other things as a team, and with individuals within the team, that we could have done better to stop the goal.
"But's a good professional in terms of how he works day-to-day. He's training well, he's adapting to the demands that we're putting on him well, in many aspects, and is really keen to help the team. I know he's going to do that in the games ahead."
McKenna added: "He was disappointed, as all the group were, but that's the nature of football and that's the nature of being a goalkeeper. We made other mistakes in the game. Probably every player on the pitch made a mistake at some point on Saturday, but when you're a goalkeeper your margins are really, really fine.
"I think he's been in good form. Up until that moment on Saturday I think he had a good game. His performances have been improving as the season's gone on. He's been helping us in a lot of different situations and I think he's been really growing into the season.
"When you're a goalkeeper or defender and you make a mistake then there's a chance it leads to a goal, especially at the level we're operating in, but it's how you bounce back from that. He's been training well.
"We believe he's a goalkeeper with really high potential who's already doing things excellently this season. He doing things that has prevented goals. One example would be his cross claiming. He stops chances for the opposition with how good he is at claiming crosses.
"He's also a young goalkeeper settling into a new area and new club with new coaching staff, new team mates and new demands. That process isn't always going to be perfect."