I hatched my first 5 clutches inside a styrofoam cooler box that my frozen rats shipped to me in, so you’d be surprised what a simple, cheap thing can do. If you had the Govee in there most of the time you should have a good record of how the incubator performed. If you want to share the log with us we could let you know how it looks.
There’s also a very high chance that since she wasn’t paired in 2 years, and seeing how this clutch went, that this was a parthogenesis clutch. Sadly, no matter what you do, these will pretty much always end up with most or all of them dying or having health issues.
Don’t beat yourself up too much over it. You did your best and did good by them by giving them a good shot at hatching. Sorry you had to go through the loss. Wishing you all the best