I'm currently embarking on a migration of a very old (Umbraco 7.2) website to v13. The first step was to upgrade from 7.2 to 7.15.11 in order to be able to progress with the uSync migrations packer. This has been done and appears relatively successful. However, what has broken is the content in the Doctype Grid Editor properties. The front-end partials are throwing errors, which is kind of okay for now, but the more concerning thing is that whilst the content still appears in the back-office (albeit the UI is different to how it was before — again, not too concerning for now) when a node is saved and published the blocks in the UI no longer have any clickable labels, so you're unable to open/edit any of the blocks. Initially I thought saving and publishing wiped all of the data but poking around in dev tools I think that it's actually "just" a UI issue where it looks like the blocks are deleted when publishing.
The original DTGE package version was 0.1.1 but v0.6.1 has been installed via the backoffice, which hasn't helped.
Does anyone happen to remember dealing with this kind of thing, and how to resolve it?