Waiver of Income - Accounting treatment

Hi, I have came across a case law in my MBA exam as below

'A' a non listed company invested in preference share of B another listed company for certain % of preference dividend 

Due to pandemic 'B' had requested for waiver of preference dividend from 'A'  and it grants the same.

Now what will be the treatment in the books of 'A' 

Kindly clarify