Morning Weaveman. First off, the good news out of this is that you didn't crash the bike or destroy the motor - either or both being quite feasible outcomes.
This whole issue of the 'failure' of the integrated nut on K&N oil filters seemed to have receded over the past few years following a fairly well publicised spate of failures. I've deliberately avoided buying any
K&N filter since the spate of failures of that integral nut.
When you say you put the filter on and hand tightened it, does that mean that you didn't touch the centre hex head at all? If so, then I'd strongly suggest that you send the filter back to K&N in this country and ask for an investigation into this since it's a reccurence of an issue which led to a safety recall some years ago :-https://www.knfilters.co.uk/recallkn204
I'd also suggest that you write a strongly worded letter of complaint to them - at very least you should get back the cost of a defective filter!
Send all product or distribution related inquiries to: email@example.com
K&N Filters (Europe) Ltd.
Unit 9 Ashville Way
Ashville, Sutton Weaver, WA7 3EZ
I hope you manage to get some satisfaction from them and would be interested to hear their response.