360 Problems shifting from 1st to 2nd near redline (F1)

I've owned this 360 for about 3 years and it has always had a strange behavior when shifting near redline while accelerating flat-out in 1st gear. If I shift at or before 8,000 RPMs it's fine, but if I wait any longer, the car refuses to engage 2nd gear when I push the right paddle and the needle just bounces off of redline until I let go of the gas. This isn't a problem in any other gear, just 1st. In all other gears I can even shift while bouncing off red line.

I have fresh fluid in the actuator reservoir and did the self-learn. I haven't removed the actuator to bleed it, but it's on the list for next year when I remove the bumper to do the gearbox oil. Gearbox oil was changed last year. According x431 I have about 83% clutch life left. I haven't messed with the PIS yet. I don't know if the previous owner has. PIS is sitting at 4.47 at the moment.

If anyone has seen this before or has any idea what might be happening, I'd love to hear it.

 

Always in sport mode. I'll give it a try in normal mode. Thanks for the tip!

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Alright, following up on this in case someone finds it useful - I think that the problem was due to a PIS set too low. I bumped the PIS by .1 a couple times and there was significant improvement. Now it only happens if I stomp on the gas from a dead stop and shift above 8,000 RPMs. Otherwise if I'm already moving and then shift near 8k under throttle it works fine. I'd bump it up some more, but I don't really have much of a need to launch from dead stops so it might be a bit before I can test this out. So I'm pretty happy with results right now.

I don't fully understand the PIS, so I can only speculate at the true cause of the problem at this point, but it seems like a good correlation. Also, the car was sometimes moving on its own without me pushing the gas in 1s gear, which as I understand it, is another indication that PIS is set too low.

To answer the questions above, 2-3, 3-4, 5-6 all worked fine under any condition. Also in non-sport automatic it worked fine, probably because the TCU didn't shift as aggressively as when it was in sport mode (automatic or otherwise).