Benrahma has been courted for months by a string of Premier League clubs, with Crystal Palace and Fulham the latest to be linked with a move for the Algeria winger.
The 25-year-old impressed off the bench but could not edge Brentford to a victory at Millwall, with Saturday's absorbing Championship clash ending 1-1.
With the transfer window shutting on October 5, Frank insisted the lack of clarity on Benrahma's future has proved problematic.
Asked if the uncertainty on Benrahma's future has caused issues or is simply par for football's course, Frank replied: "My answer needs to be both. I think all of us, including him, would like to have answer; stay or go.
"I don't know if he will be here after the transfer window.
"But that's part of football, so we deal with it.
"And I must say that Said has been bang-on in terms of attitude and being a top professional. That's just the transfer window.
"I think he did fairly well, it wasn't his best 20 minutes but he still showed good actions and put in one unbelievable cross. One inch more and it's a goal for Ivan Toney.
"I'm happy with his attitude. I don't know what's going to happen, I can only guess.
"If he's here, then I'm more than happy to have one of the best attackers in the division."
The stranded Jansson lost one of his fluorescent orange boots and wound up in a heap on the turf as Bennett whipped in the pivotal ball for Wallace's opener.
Striker Ivan Toney got off the mark for Brentford since his £5million summer switch, casually walking three steps before rolling home a first-half penalty.
Frank hailed former Peterborough man Toney for steady improvements since his transfer, backing the 24-year-old to shine as he warms to the Championship task.
"There's so much more to come from him," said Frank.
"We've seen a steady rise in performance from him in the last three games.
"His intensity in the press was much better today, so I'm very pleased with that.
"His link-up play, everything from a long-ball battle to a set up or a flick around the corner, that was good as well.
"And then his positioning in the box too, it's all going in the right direction. But especially his pressing today, that was very good."
Millwall boss Gary Rowett hailed the Lions' unbeaten three-match start to the campaign, warning Championship foes to expect a battle against his side this term.
"We're not an easy team to play against, we know how to compete and make it difficult for teams," said Rowett.
"I'm pleased with the start to the season. Last year we finished just outside the top six with a poor start to the season, so this is encouraging.
"We had a really good start and it was a well-worked goal.
"I was a little disappointed with the penalty to be honest, I thought it was a little soft.
"We had one late on from Norgaard on Bodvarsson that was three times as bad and nothing is given."