If two changes are one after another, a strange behavior is observed when the cursor is sitting just between both changes. A simple variant of the problem is easily reproduced this way:
a) create a document and write four words.
b) turn on Changes Tracking
c) Delete the third word and write some other word instead. Now an "addition" change should be next to an "deletion" change
d) delete the fourth word, so there is one more change after the changes that are together
e) Move the cursor to the begining of the document and select "next change" from the changes toolbar. The first change is selected
f) Accept the change. Now the cursor should be sitting in front of the second change.

  At this point the bug can be tested: the "Accept change" and "Reject change" toolbar buttons are grayed out, so we can not accept the next change. If we press the "Next change" button, the change right next to the cursor is skipped and we are taken to the final change. This behavior is particularly annoying when small changes (one-word changes, etc) are made to a document.

This was tested in 5.2.6.2 release in Debian. LibreOffice installed on Spanish (I guess it's language independent)

I hope this is clear, I can attach an example if needed