Sir, it is so because your supplier has not shown it in his GST Return or not filed his return, you can take ITC on the basis of Invoice but ask your supplier to update it ASAP as, it is like DVAT, you have to match your purchase with supplier sales otherwise you may have to pay this ITC amount taken.
Agree with Mr. Ankit. You can take ITC and ask your vendor to update the same in GST-1. However if the vendor denies to do the same, you will have to reverse the ITC which has been claimed
and in order to claim ITC, one of the condition as per section 16 is that the payment of tax to the credit of the government collected by the supplier is mandatory. If the supplier has not deposited the same then you may have to reverse the ITC as said by Ankit ji and Sahil ji.