Firefox overwrites current tab with "homepage" tab on start up

Since the last Firefox update, I've noticed an issue whenever I launch the browser. I have it set up so that I have multiple tabs open, and it's set up so that when Firefox starts up, it opens all of the previous tabs and starts me on the tab I was on when I closed the browser previously. Now whenever I start Firefox, it opens to the last tab I was on, but said tab opens on my current homepage instead of the website that tab was on previously. I experimented by changing my homepage to "Youtube.com", picked a different open tab, closed Firefox and opened it again and sure enough, the tab was now on the Youtube page instead of what it had been previously. Is this just a bug of the current Firefox version, or is there something in settings I can do to fix this?