I believe I may have found the solution to the M-1 issue because of the employee retention credits (from another online message board).

On the books, I show the employee retention credit in other income. On the tax return, I don't show it as other income but rather as a reduction of wages (in the 'less retention credit box' in lacerte). Naturally, the other income is not being reported in lacerte because it is already showing as a reduction of wages and with a corresponding m-1 adjustment in lacerte and on the tax return.

Since the other income is not reported in Lacerte, an M-1 adjustment is needed for 'income recorded on books and not on schedule K,' using an appropriate explanation.

In any case, this will balance the balance sheet.