I sold some Employee Stock Purchase Plan shares on 12/31/2014. As far as I understand, the ordinary income portion of the sale should have been reported on my 2014 Form W-2 from my employer but was not. The sale was reported on a 2014 Form 1099-B from the brokerage. I calculated and reported the ordinary income portion of the sale on my 2014 tax return. The shares were acquired in July of 2014, the same tax year in which they were disposed.

On my 2015 Form W-2, the ordinary income from that sale was included in the taxable wages in box 1. I contacted my employer who simply replied that income is taxable in the year it is received, which doesn't seem like it applies to this case since it's imputed income, not wages paid. 

Should I keep pressing my employer to issue a corrected W-2? If not, what should I do?

UPDATE (even though I may literally be the only human to ever encounter this situation, notice, and care):

I called the IRS live human support line multiple times, and was finally and definitively told that they're not trained for this kind of question. 

I was directed to Publication 525, which I see specifically states:

> 
> Your employer or former employer should report the ordinary income to you as wages in box 1 of Form W­2, and you must report this ordinary income amount on Form 1040, line 7. If your employer or former employer doesn't provide
>  you with a Form W­2, or if the Form W­2 doesn't include the ordinary income in box 1, you still must report the ordinary income as wages on Form 1040, line 7, for the year of the sale or other disposition of the stock.
> 
> 
> 

Therefore, it is clear that the income was taxable in 2014.

I may need/be able to file form Form 4852, Substitute for Form W-2 with an amended return for 2015.

UPDATE 2: 
The IRS accepted my amended 2015 return and issued a refund by paper check, including some interest (which is taxable).