I've tried over and over again, initially, I thought I didn't input everything actually, but on several other trials, I was careful enough to copy and paste everything till the end, but still got invalid signature.
Could this be device related, I would suggest you try doing it over again on another device and see what result you get.
I am also going to try this again on my personal computer, I've tried multiple times on my mobile phone, but it always returned back as invalid signature, mycelium also recorded it as an invalid signature.