Okay, I have no idea what went on, but NOW Unlimited Ammo and Use Node works as it should, which is weird. At the beginning of the game, before the trainer was released, I had only one node. Then the trainer was available. I enabled this cheat and chose to upgrade my Cutter with my one node, hoping to have unlimited uses. It didn't work. That one node became zero nodes. However, later on I found another node and enabled Mega Nodes on Pickup to give me 99 (then disabled it as per instructions), which worked. When I went to the upgrade station, I turned on Unlimited Ammo and Use Node and tested out if it would work. It did. My node count did not drop. I even tried it on my Cutter. No drop in count.
So, no idea why all of a sudden it works. Unless it's because I only had one node and the trainer doesn't recognize a single value. That's my only guess, as I did that Mega Nodes on Pickup a second time with another node before going to the upgrade station and I then had a total of 198 nodes. However, when using the Unlimited Ammo and Use Node at the upgrade station, one upgrade took that 198 down to 99, but the count never dropped from that with each subsequent upgrade.
Either way, that option works now, so I'm all good. 🙂
I was having the same issue with credits but then everything worked after I collected a second set of credits. Then I had a huge amount of credits.