page moving issue - legacy bug?

This may be a legacy bug. I saved my file back to X8 which was the last version I owned before 2019 - which I purchased when I got a new computer. My file has about 70 pages in it. I noticed that one of the pages moved - just a couple of pages back - in X8. That was last week. I fixed that with Page Sorter. Yesterday it had moved again. I know nobody wants to hear this. I am retired and this is the first really long document I have worked in since perhaps X4. I don't remember ever having this issue in any version of Draw - and I have been around since version 3. The only long files I ever worked in in version X8 were about 12-20 pages long and I never experienced this issue. However, I was on an older computer with those files - one that will no longer take the windows updates. That is why I bought this new one. Could this be the "variable factor" causing this issue - my new machine?