@Mateja brings good new ! This issue is not model year dependent ! Also, apparently, it is a rare occurrence..(?)
Perhaps there is a procedure that must be done in definitive steps - in order for any model year EFI KLX to "accept" the Clutch Switch Mod..?

I really have no idea idea what it depends on. Dont remember doing anything different back than. I removed and “reinstalled” this mod like 3 times a month ago, and none of the attempts ended with flashing FI.

But I have been thinking about the things that were different on the bike when I had the problem.

I can recall that my battery was barely charged when I tried. My battery was always drained because the stock cable harness could not deliver enough power from the generator to charge the battery. This problem has been solved since then.

Don’t know if it has anything to do with the FI problem, but thats the only thing I can think of.