Yep.
Originally the UK was supposed to have the source code, its the digital “key” that unlocks the F-35 software (try and tamper without it and the code erases itself and you get left with a useless plane).
Lockheed/the US refused to share it with the UK, so we couldn’t integrate it ourselves, so the UK and Italy paid MBDA and Lockheed Martin to do it in America, this was due by 2015, MBDA got their bit done, Lockheed Martin have been delaying it for years, closest estimate is 2030.
Conveniantly it was suppised to be part of the Block 3 software enhancement, now its Block 4, which is the same one that AIM-260 will be part of… can’t have Europe stealing the US’ export orders now can we?
Australia is reportedly interested, the aircraft will be tailored with them in mind as well as the UK, Japan, Italy and likely Saudi Arabia also.
There are a couple of reasons in my opinion
The UK is trying to buddy up more with CANZUK which means a Pacific shift with thinks like AUKUS, the existing UK Indian ocean and Australian bases etc whereas France is still focused on the Mediterranean and NATO regions to a higher degree than the UK.
Finally in the nicest possible way, its because France/French companies are too defensive and don’t want to “share” development and manufacturing we saw how France left Eurofighter partially over CATOBAR which is perfectly fair but also the first issue was because they didnt want to use a blatantly superior RollsRoyce engine over the SNECMA/Safran engine developing 10kn less.
On Tempest the UK has said its willing to compromise, we will take a back seat in some places, and lead in others. This is about the UK and Japan and Italy sharing knowledge where the others lack it and selecting the best possible option for the best possible aircraft both in performance and cost.