Importing project missing merge requests, pipeline history

I’ve been trying to move projects from our self-hosted gitlab (v14.1) to I’ve done this by exporting the project, then importing it.

Half of the projects I’ve imported are missing all the MR history and pipeline history. The exported projects range in size from 1 MB to 1 GB - but the size doesn’t seem to make a difference. I’ve read through the following issues that all say the issues is resolved, however this isn’t the case for me.

What can I do to get these projects moved into with their full history?