Did you create chapter markers in PR? If so, those should come into Encore. There have been changes in markers across several versions, so may not work where you have a mix of CS4 and CC.
When I have had problem projects to re-create, I have gone back to the original, written down the timecodes, and entered them in Encore and marked chapters. Doesn't take all that long.
You can "import as menu" the menus from the original Encore project folders. You have to do all navigation, etc.