Numbers - INDIRECT Call Error
Is it possible that the formula you have in cell B1 in the Amortization table is slightly different than the one you typed in the question above?

After creating two tables with the same column and row names as yours, I am able to replicate your problem and get the same error message which is "This formula can’t reference its own cell, or depend on another formula that references this cell". This happens, for example, if I place the following formula which has no space after the word "Rate" in cell B1 in the Amortization table:

=INDIRECT("Interest Rate"&amp;E1)

However, the formula in cell B1 works correctly if I add a single space after the word "Rate" but before the ending double quote as follows: 

=INDIRECT("Interest Rate "&amp;E1)

The same error can also be caused by the words "Interest Rate" to be slightly misspelled in the formula in cell B1 even if the space after the word "Rate" is actually there. 

Interestingly, the first formula above (or any version of it with a spelling mistake) causes a different error message ("The formula contains an invalid reference") if it is placed anywhere outside the header rows or header columns.

I have done all of the above via Numbers v6.1 but I doubt this makes any difference as far as the problem you are experiencing is concerned.

Hope this helps.