Cannot migrate to 4.8…should I revert to 4.7.5?

I am a developer helping a client migrate their WP site.
The source site is in WP 4.7.5, and was partially migrated into a 4.7.5 site.
Then I made the mistake of upgrading to WP 4.8 on the target site….

I got partial imports of content to work, with users, pages and posts. But the posts has the wrong authors, so I was trying to fix that, and ended up needing to reset the 4.8 site (a feature I do not see in 4.7.5)

However, when I export everything from the 4.7.5 site, and try to import into the 4.8 site, the only data that comes across are users — no posts or pages.

After repeated attempts, I am convinced this export/import using the standard WP tool will not work; and so now believe the safest thing to do is start over with WP 4.7.5 on the target site…then at least I will know it’s not a version issue.

Has anyone else seen this problem? Or would anyone else have a different suggestion on how best to proceed?

TIA,
–Rick