Yes, you can file your 2018 taxes even if the 1040X for 2017 hasn't been processed.
If you have the self-selected PIN from last year then you can e-file, or you can try to see if the return will go through with the AGI from the 1040X or from the original return. Otherwise you will have to print and mail the return.
Hi were you ever able to resolve this issue? im haviing the same problem my tax return from last year has not been rejected or accepted. Its sitting in "still being processed. my tax return was rejected today becuase of my AGI. I have not received anything yet.