I have recorded this (.mp4) but no idea how to upload it here.
Go to settings > texturepacks
Whenever putting like 2 outdated texture packs on the right side some arrows will dissapear when clicking on them and not work, also when the texture pack is already at the top an arrow-up can still appear, there are many more weird things I have in a small recording.
Whenever clicking save and opening the texturepack GUI again everything is fixed
You can just attach the video to this ticket by using the "Attach file" button.
If the video is too large, you can upload it somewhere else and then link to it here.