is there any grace period to MNP back to Hotlink , after MNP to other telco ?

i was a hotlink customer , ported out early this month to Umobile . however when i try to MNP back to Hotlink , it shows – Sorry, you have entered an invalid ID number, mobile number, or both –

Do i need to wait 1month only can MNP back to Hotlink Postpaid ?