Jpez
Down on the left!
Are you confident all the strands of the old inner came out of the outer and all of the strands of the new inner came through the outer? And you have correct routing of the cable through the derailleur?
I have has a couple of strands from the inner get unwound and jam inside the outer before, and I have definitely not correctly routed cable through a derailleur once or thrice.
Oh and...is the cable firmly secured to the derailleur? That's another favourite of mine. A lift turn of the hex key to position the cable while I fidget and then forget to finish the job properly...
So replaced the inner and outer and had a good look and appears I tightened down an external alloy cable guide slight twisted and essentially crimped the outer creating a tight spot. Never come across that one before.Did the little noggin thing on the end of the cable fully drop into receptacle (technical term, lol) in the shifter? I've ballsed that up on Shimano shifters a once with similar result.