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In that case I would try a test: Export the INDD file to an IDML file. Re-open that IDML file and save-as to a fresh INDD file. See if the problem still exists. 

Also, make sure the textframe that contains the table is not locked in any way.

This looks like cells in a table. Cells must not have multiple empty hard returns. Generally cells should not have hard returns at all. If you are using the return key as if your typesetting computer is a typewriter, you are doing it incorrectly employing a typewriter habit from the past. Can you backspace all those hard returns?