RecyclerView sets wrong MotionLayout state for its items

First: I created a sample project showing this problem. By now I begin to think that this is a bug in either RecyclerView or MotionLayout.

https://github.com/muetzenflo/SampleRecyclerView

This project is set up a little bit different than what is described below: It uses data binding to toggle between the MotionLayout states. But the outcome is the same. Just play around with toggling the state and swiping between the items. Sooner than later you'll come upon a ViewHolder with the wrong MotionLayout state.

So the main problem is:

ViewHolders outside of the screen are not updated correctly when transition from one MotionLayout state to another.

So here is the problem / What I've found so far:

I am using a RecyclerView.

It has only 1 item type which is a MotionLayout (so every item of the RV is a MotionLayout).

This MotionLayout has 2 states, let's call them State big and State small

All items should always have the same State. So whenever the state is switched for example from big => small then ALL items should be in small from then on.

But what happens is that the state changes to small and most(!) of the items are also updated correctly. But one or two items are always left with the old State. I am pretty sure it has to do with recycled ViewHolders. These steps produce the issue reliably when using the adapter code below (not in the sample project):

1. swipe from item 1 to the right to item 2
2. change from big to small
3. change back from small to big
4. swipe from item 2 to the left to item 1 => item 1 is now in the small state, but should be in the big state

Additional findings:

• After step 4 if I continue swiping to the left, there comes 1 more item in the small state (probably the recycled ViewHolder from step 4). After that no other item is wrong.

• Starting from step 4, I continue swiping for a few items (let's say 10) and then swipe all the way back, no item is in the wrong small state anymore. The faulty recycled ViewHolder seems to be corrected then.

What did I try?

• I tried to call notifyDataSetChanged() whenever the transition has completed
• I tried keeping a local Set of created ViewHolders to call the transition on them directly
• I tried to use data-binding to set the motionProgress to the MotionLayout
• I tried to set viewHolder.isRecycable(true|false) to block recycling during the transition
• I searched this great in-depth article about RVs for hint what to try next

Anyone had this problem and found a good solution?

Just to avoid confusion: big and small does not indicate that I want to collapse or expand each item! It is just a name for different arrangement of the motionlayouts' children.

class MatchCardAdapter() : DataBindingAdapter<Match>(DiffCallback, clickListener) {

    private val viewHolders = ArrayList<RecyclerView.ViewHolder>()

    private var direction = Direction.UNDEFINED

    fun setMotionProgress(direction: MatchCardViewModel.Direction) {
        if (this.direction == direction) return

        this.direction = direction

        viewHolders.forEach {
            updateItemView(it)
        }
    }

    private fun updateItemView(viewHolder: RecyclerView.ViewHolder) {
        if (viewHolder.adapterPosition >= 0) {
            val motionLayout = viewHolder.itemView as MotionLayout
            when (direction) {
                Direction.TO_END -> motionLayout.transitionToEnd()
                Direction.TO_START -> motionLayout.transitionToStart()
                Direction.UNDEFINED -> motionLayout.transitionToStart()
            }
        }
    }

    override fun onBindViewHolder(holder: DataBindingViewHolder<Match>, position: Int) {
        val item = getItem(position)
        holder.bind(item, clickListener)

        val itemView = holder.itemView
        if (itemView is MotionLayout) {
            if (!viewHolders.contains(holder)) {
                viewHolders.add(holder)
            }

            updateItemView(holder)
        }
    }

    override fun onViewRecycled(holder: DataBindingViewHolder<Match>) {
        if (holder.adapterPosition >= 0 && viewHolders.contains(holder)) {
            viewHolders.remove(holder)
        }
        super.onViewRecycled(holder)
    }
}