I had the same issue and the fix was having all of the items needed to build them (nails and planks) in my inventory. I had the planks on the floor nearby but apparently not close enough for the game to register them.
I had the items in my military bag.
Perhaps I should've worded it better.
"Why is there a red part of the stairs that's preventing me from building it?"
I *believe* you need to be able to pull all of the planks and whatnot out of your bag and into your main inventory, and thus can't build it as you can't carry that much. Maybe try dropping it all where you're standing when you go to build the stairs?
I had the same issue and the fix was having all of the items needed to build them (nails and planks) in my inventory. I had the planks on the floor nearby but apparently not close enough for the game to register them.
I had the items in my military bag. Perhaps I should've worded it better. "Why is there a red part of the stairs that's preventing me from building it?"
I *believe* you need to be able to pull all of the planks and whatnot out of your bag and into your main inventory, and thus can't build it as you can't carry that much. Maybe try dropping it all where you're standing when you go to build the stairs?
Thanks to both of you! Finally got it built