Lifter stuck?

I’m sorry but this is lengthy. I want to try and give all the info. This may be simple to some of you guys but I just can’t figure what happened. And I would like to make sure what happened so it doesn’t happen again. 340 engine, it was built and running when I bought it a couple of years ago. Started not running well after all different attempts at tuning etc, so I pulled it while doing some other work to the car and disassembled it. Found a cam lobe starting to go and a divot in a lifter. Went ahead and pulled it all the way apart cleaned and inspected everything. All of it looked like new, pistons (lots of carbon on piston tops) but other wise looked really good, rings, bearings etc all look good Previous owner told me it was fresh but wasn’t sure. Anyway put a new cam in it, timing chain and gears all new gaskets etc. followed the cam break in precisely. It’s a lunati cam, I used their break in oil and cam lube. I had a helper watching coolant level, oil leaks etc. all went well. Changed the oil, used valvolone vr1 and reinstalled my inner springs. Was out driving it last Saturday and noticed what sounded like a lifter ticking. Oil pressure and temp were good. Pulled over and cked it, sounded like a lifter but wasn’t terrible, so I turned around to head home, only a couple of miles. The further I drove it the worse it got. Pulled the valve covers to ck it and found a lifter that was basically doing nothing, the rocker arm just flopping around, but only one of them. I like to never got the lifter out of its bore, it would move up and down but would not come out. Finally got it and it’s chewed all to crap. The cam lobe is toast and the lifter looks like it was stuck in its bore and the cam just carved a 1/4 notch on it. Is this possibly an oiling issue. It was the exhaust lobe for cylinder number 8. Could it have gotten some trash in the oil path and caused it not to oil and stick? Anybody seen this or have any ideas. I can take a good lifter and it slides in the bore with no issues. Smh. Thanks and again sorry for the lengthy post.