I have some news for you: I have had very similar problems with my Lotus Evora S IPS MY2012 was in at the Dealership here in Belgium until yesterday for the second time in a month with the IPS stuck in 5th gear and the engine MIL indicator as well as the transmission indicator lights having switched on. I had to stop the car to have the gearshift working again. When restarting the car everything was OK again, although the indicator lights remained on.
My superb dealer had had the car in for two weeks after the first time, diagnosed the problem in collaboration with Lotus cars as a faulty solenoid in the auto gearbox, and replaced it.
The second time, he organized for two Lotus engineers who are responsible for the gearbox and the Lotus software running it, to come over to Belgium (fairly close to Norfolk, UK, but still far away from home for these guys). The engineers worked for two days on end, and drove over 350 kms with all their factory programming gear attached to my car. They found out that the way that their software was written is not suited to my driving style, which I admit is sporty, with frequent manual overrides in 1st gear high up into the revs (they shouldn't make the exhaust sound so bloody sexy!). They completely rewrote the software to also accommodate my driving style, and will make the software available to all IPS cars somewhere in January 2013, after their Xmas holidays. Now that's talking isn't it. Although I did feel frustrated at times due to the gearbox problems, I do feel more part of the Lotus family.
By the way, the engineers told them that a Lotus Evora S IPS driven on a daily basis by a Lotus engineer got stuck in 3rd gear as well, with problems which are exactly yours. I do hope that the new software written on the basis of the faults they acquired from my car, will solve your issues, as well as theirs.
Thanks for the update. I've had no problems since. The car is now under cover on life support (battery maintainer) - winter has arrived. The dealer said the software is up-to-date. I'll send them your response and will be on the look out for a software update next spring.
My driving style is probably tame compared to many. I use sport mode and paddle shifters when I'm on the expressway on ramp, and when I want to pass quickly. The car was very enjoyable at the Tail of the Dragon (google it). Sport mode and paddle shifters all of the time. It ran perfectly.
It was odd when it had its breakdown - simply started up to go home.
There are times when I wonder if I'm driving an excellent sport car, or a computer. I down loaded most of the Evora manuals and read through the error codes, what causes them, and what is tested. As a retired software engineer, I would be amazed if the programming is correct. There is most likely too much interaction between faults and how one fault affects another.
I also received a two page explanation from my dealer via Lotus explaining how faults are now handled. A brief description:
Pending: A malfunction is detected by engine diagnostics generating a relevant fault code, but the severity of the malfunction is not considered great enough to illuminate the check engine or wrench Tell Tale. A pending fault code may change to a Confirmed fault code if detected on the 2nd drive cycle if the same malfunction is detected.
Confirmed: The malfunction detected was by its severity sufficient to illuminate the check engine or wrench Tell Tale.
Permanent: A permanent fault code is also stored in the ECU at the same time as the Confirmed fault is generated (but only for the check engine Tell Tale). Note: A permanent code will not automatically delete from the ECU's history even if the Confirmed code has been "cleared" and the check engine light extinguished.
There is another full page of explanation.