I updated the bug using one of the experimental builds.
0.B 251207a
SDL
Windows 8.1
ACTUAL
long underwear top (fits) + kevlar vest (fits) + backpack => 1+0=1
long underwear top (fits) + kevlar vest (fits) + backpack + quiver (fits) => 1+1=2 <----- This number
EXPECTED
long underwear top (fits) + kevlar vest (fits) + backpack => 1+0=1
long underwear top (fits) + kevlar vest (fits) + backpack + quiver (fits) => 1+0=1 <----- or this number
Long underwear and quiver both “layer easily” and the other two do not. My expectation is that this behavior would be correct it Quiver was not a “layer easily” item. Quiver even has explanation text that says “This small item won’t encumber you”. Strangely under the “Re-layer armor/clothing” menu it’s listed as “It is very bulky”
This also reproduces using large quiver in exactly the same way.
Extra note: for some inexplicable (to me) reason:
ACTUAL
long underwear top (fits) + trenchcoat (fits) + backpack => 1+0=1
long underwear top (fits) + trenchcoat (fits) + backpack + quiver (fits) => 1+0=1
Perhaps this has to do with the trenchcoat property called “This is worn over other clothes”?