The front passenger seat doesn't recline. The handle seems to work perfectly
This one is pretty easy to figure out. Your seatback isn't working correctly. Okay, I'll grant that my answer may seem pretty obvious, but, it really isn't, please hear me out.
When you yank on the handle the pawl that engages and locks the seatback into position, so that it won't move, is removed from its receiver. In this mode, the seatback moves freely back and forth as there is nothing to prevent its movement back and forth. You use this movement to find the exact seatback angle for you and when you have, you release the handle and the pawl is reengaged and the seat is locked. (There are various safety features involved that assure you that your seatback will remain locked in position. While the pawl and receiver are quite sturdy, you cannot depend on them alone in a crash. So, there is at least one interlock device that engages when the pawl goes home. The interlock helps to "rigidize" the seatback so it doesn't move.)
What is happening in your car's case, though is this, the interlock may be broken so that even if the pawl releases from the receiver, which it apparently is doing, your seatback remains locked because the linkage between the handle, pawl and the interlock is not working. You will have to have the interlock (it could be that device) and its linkages repaired before the problem will clear up.