Ferrari's rivals remain unsatisfied with the way an investigation into the legality of the Italian team's engine was handled over the winter.
Responding to concerns from other teams last year, F1's governing body, the FIA, conducted an investigation into Ferrari's power unit over the winter, eventually reaching a confidential settlement with the team.
With no further information on what the investigation had found, seven of F1's 10 teams accused the governing body of a lack of transparency, resulting in the FIA admitting it had held doubts over the legality of Ferrari's power unit, but was not convinced it would reach a conclusive outcome by taking the issue further.
It looked as though the subject would explode into a much bigger row ahead of the Australian Grand Prix, but events were overtaken by the cancellation of the race and the coronavirus pandemic putting the season on hold.
However, speaking ahead of the first race of 2020 this weekend in Austria, both Red Bull and Mercedes made clear that they were still unhappy about how the investigation was handled.
"Look, it does sit uncomfortably that there is an agreement that has been entered into about the legality and conformity of a car," Red Bull boss Christian Horner said. "That immediately draws you to think what is in that agreement? What does it comprise of because obviously in our minds a car is either legal or illegal?
"Now obviously questions have been raised with the FIA; the FIA have said they would be happy to disclose that document but of course they need the clearance from the other signatories so obviously it does nothing but promote suspicion when there are private agreements about legality and conformity.
"The healthiest thing would be to get it on the table so everybody sees what it comprised of. The FIA have said they are willing to do that, it would be great if Ferrari were prepared do the same so it puts it all to bed."
In the aftermath of the Australian Grand Prix cancellation, Mercedes pulled its support from the group of non-Ferrari powered teams asking for further clarification, but team principal Toto Wolff said it was simply in light of wider events and, given Mercedes' efforts to push its own power unit programme to the limit to beat Ferrari, he still wants answers.
"We didn't back off," Wolff said. "We decided in Melbourne that for the start of the season this additional controversy plus corona starting to get really bad in Italy, was not the opportune moment.
"I would very much agree with what Christian said: In this day and age, transparency is extremely important and good governance -- it's extremely important. And it may well have been good governance but if you don't know, it's difficult to judge so in the position that we are in is that we are monitoring the situation.
"We are not happy about last year. It has stretched all of us to a point to be competitive against Ferrari where it was difficult to cope and therefore let's wait and see how the season starts and gets going and we will then reassess for ourselves and probably with the other guys who were upset."
FIA president Jean Todt has said he is willing to release details of the investigation if Ferrari agrees, but team boss Mattia Binotto made clear he was not willing to do that.
"The answer is quite straightforward," he said. "First, there was no clear breach of the regulations. Otherwise we would have been disqualified. The reason we don't want to open [the details] is simply because whatever we would need to explain is IP, intellectual property to our project, to our power unit and no one in the paddock would be happy to release information on their design and their projects.
"It's IP, it's confidentiality, it's intellectual property protection and that's the reason why we are not keen to do it."