This is a new bug that began only after I updated to version 2.2.0 in Windows 10. Yesterday, before I updated the software, I did not have this issue.
After the update, I started seeing this message when I tried to export an SVG under specific circumstances:
Then the program would then freeze and I would have to kill it using Task Manager.
This was a consistent bug. Here is how I replicated it:
1. I opened an Affinity file. (Which file, which version of Designer it was created in, where it was located, and whether I made any changes to it did not seem to matter. However, I did not test this very extensively before I accidentally fixed the bug.)
2. I exported it as an SVG using my custom export preset, which I had created in the previous version of Designer 2.
3. When choosing a location for the save file to go, I saved it over existing SVG that was located on a separate drive. (If I saved it as a new file, the bug did not occur. If I saved it over an existing file located on my C drive, the bug did not occur. Whether the existing file was created in Designer 2.2.0 or an earlier version did not seem to matter. However, I did not test this very extensively before I accidentally fixed the bug.)
4. Upon saving the file, the program would display the "Export item" message above and freeze.
Here is how I fixed it (or at least how I think I fixed it):
1. I switched to the default export preset and exported the file. It exported successfully.
2. I switched back to my custom preset and exported the file. It also exported successfully.
After doing this, I have not had any more issues. It seems that switching to a different export preset may have perturbed the bug out of existence, and now I can no longer replicate it.
Hopefully this may be helpful to anyone else experiencing a similar issue or to any developers trying to narrow down a related bug.