I have just experienced exactly the same thing..
Just moved house, so doing a late upgrade..
My HX effects unit does the same thing.. (I have in the past had issues with the unit - comms to PC still dodgy), but last couple of updates was building back my confidence.. Until this..
At least it may be a bug that needs fixing..
I had used all 9 blocks, ( patch made up from new) only using about 3 blocks actively..
When using 1Sw looper - nothing happened.. No LEDs etc. Then about 2mins later my guitar noise after pushing button comes through. Like you, I have to cycle power to reset..
I will try raising a ticket with L6 support..
Simon