Day 310-something or maybe 320 something, not exactly sure. Hurricane season. I decide to get more cacti from the volcano, drink my coffee, equip my walking stick then make my way to the volcano. I traveled and arrived during the night. Once inside the Volcano, make it to my mini-base, place the bird cage I was holding on to as the day arrives. To my surprise, despite it being hurricane season I find all the elephant cacti active. I kill one myself, decide that it isn't worth wasting armor on it, so lure some dragoons nearby to kill 2 more, dig them up. It s almost dusk, so I leave the volcano as the dusk arrives. Yet, I'm surprised again. It was (almost?) dusk when I was leaving, but when I was out it was bright day light. I look at the clock, which now shows day 400, early morning. I go to my base, check perishables, nothing has turned into rot, so they definitely didn't advance forward 80 days.
Edit: I sent a link to a copy of my saved game to "CapyChristian" in a forum message. This is after the issue, unfortunately I don't have one from before. Also to add to above. The saved same in the game menus also show 400+ days.
1- Enter volcano 2 -??? 3- Day count advances.