Merge & Split proposals

We have tried to perform the merger and split of several proposals with an administrator/collaborator/process evaluator and it gives us the error of the image.

Checking the production log there is no WARN or ERROR :/ version decidim: 0.21 (we have tried different configurations, enabling everything possible in the global component and phase configuration, and all have resulted in error).

Can you upload this procedure to the official documentation? It should also be specified a little more because the error occurs. Thanks.