Problems With New Battery In Street Twin

Last week I installed a new battery in my 2018 Street Twin. The battery was fully charged when I fitted it. The day after fitting the battery I took the bike for a ride. It started first time and the bike appeared to be running well when I took it to the petrol station to fill the tank. Then I took off for my ride, the first one for a few months.
However, after about fifteen minutes, travelling at about 60mph on a major road, the engine cut out. I pushed the bike to a nearby service station and tried to restart it, but had no joy. There was little life in the instrument panel if I remember correctly.
I was ready to ring for assistance when I tried the ignition another time. On this occasion the engine started and, much relieved, I set off for home. I took the long way back, putting the bike through its paces, doing twenty miles or so, and the bike was running smoothly.
At home I checked the battery installation, undid the terminals and reattached them. I then tried to start the bike again but it behaved in an erratic fashion, sometimes starting and sometimes not. I was reluctant to take the bike out on the road again in case it stranded me.
Is there any possible reason for my bike's behaviour following installation of a new battery? I've tried starting the bike a number of times in the garage and there have been no problems. There are no lit warning lights on the instrument panel but I haven't yet take the bike out on the road again.
Any possible explanations and reasons for my bike's erratic performance will be very gratefully received. Is it likely to have been a 'one off?' I've googled left, right and centre but haven't got any closer to a plausible answer.
Thank you.