@ richard
I persisted for hours trying your method (with appropriate pin changes) and had no joy
all you have to do is post the code for your attempt and i will have a look


hints

serout2 PORTC.6,16468,[13,10,"RE_val ",dec5 RotEnc1_val] once in an isr is bad twice is just asking for trouble , use flags

using a pin change int for a switch is a giant over kill