Yeah, sorry to hear that too. I was bummed out when I had to redo all of the nights because I wanted to download the new update/patch. It's not a bug, I just don't think they have a good save mechanic when switching versions.
Anasemikku
Recent community posts
Honestly, not really. I haven't really came up with ways to survive the animatronics since I haven't felt the need to. Just stay in the vents, listen for footsteps (kind of hard I know), like you said Bonnie goes to kitchen a load of times, Chica just walks around places. Not sure on how to help you by giving tips to be honest, mainly just trial and error.
It will not be obvious that the item you are trying to look for is right there, that's why you just check every location that it could possibly be in. The vents do connect to other rooms, office to arcade, that vent near the exit leads to the Cove, etc. Regardless if you have the flashlight on/off and are crouching, they will still get aggroed and will hunt you down.
For the items, I recommend finding out where each item spawns (and if they spawn in different locations). This will help you because they will always spawn there, and won't spawn randomly on the map so it'll make it easier for you to just find that location you mapped out, and grab and run. For night progression, vents are your best friend to surviving the night, either stay by one near the exit or just run around and go into one when they're nearby. I used to just sit in a vent the whole time and walk out, but I could never see since my flashlight would just run out and my sanity would make me see hallucinations. I have found out a place to where you can just glitch and sit there for the rest of the night near the exit until it opens, pretty easy to do.