Looks like I made a mistake getting an Amp with any sort of software attached. I'll know in future.
I'll also avoid Line6 like the plague - as this should not take long to resolve, if they wanted to look after their customers.
We don't need any support or additional features, just a release of the existing app as a 64 bit app (which will hit everyone, eventually, when they upgrade their version of Android).
If they can't be bothered to do that, they could instead release the source code as open source (as it's now obsolete and unsupported) so that someone else can update it to 64 bit..