Ah, I did not realize the ground was a destructible as well. That makes more sense.
Something you could try to do that requires a little more setup, but it can work in situations like there where something is bugged.
For the ground mesh you can make this a regular static mesh in a Blueprint, instead of being a destructible. Then in the original wall DM you can set this to be world supported rather than Form Extended Structures. This will allow the DM to stick to the static mesh (so long as the static mesh is not set to movable).
Then with a little bit of logic setup in your Blueprint you can set the ground mesh to spawn in pre-defined fractures from the original mesh. The original mesh can be cut into pieces in your modeling program. This is how Destructibles would be used on mobile, but this application is good for other situations as a workaround or an instances where you don’t want the costly effect of DMs using extra resources on the CPU.
I know that’s a high-level setup, but it’s where I would start investigating something like this.
I hope it helps.