So this turned out to be harder than I thought, and I know the solution isn't optimal because while the next/previous links will work in Hybrid mode it doesn't cache the post so the entire page reloads.
What you need to do is edit showthread.php file.
Find the line:
Code:
if ($threadedmode == 2) // hybrid display mode
And "comment it out" (make it)
Code:
//if ($threadedmode == 2) // hybrid display mode
then find the line
Code:
else // threaded display mode
and comment it out too...
Code:
//else // threaded display mode
Then save changes. (Maybe backup the original file first.)
In my testing the next/previous worked in Hybrid mode after these changes.