In Pages 5, how to get a table to span multiple pages?
Solution 1:
Looks like it happens because "Prevent widow & orphan lines" option is activated by default.
Select the text where the table is located, in the Inspector panel look for "More" and uncheck "Prevent widow & orphan lines". I had the same problem and found the solution this Apple Support Communities thread.
Solution 2:
As of Pages 6.3.1 it looks like the situation has got worse!
Within tables there is no "Prevent widow & orphan lines" option in the More tab. It's still there in normal text.
And if a table cell exceeds page limits it's simply truncated and there's no way I can see to recover the text.