Changing Balance in Audio Mixer can irreversibly mute a channel

I have a stereo audio clip on an Audio track. If I change the balance of that Audio track in Audio Mixer to either minimal or maximal value (-50 or 50), then one channel is muted as expected. If I then save the project and reload it, then the balance of this track is set back to 0 in Audio Mixer, but that channel is still muted, making it impossible to make it audible again. If I then change the balance to the extreme value of the other side, so that the other channel is also muted, and save and reload again, then balance is set to 0 again and both channels are irreversibly muted.

I'm using Kdenlive 19.12.2 AppImage on Linux Mint 19.