this is quite a common issue after port in/out..

in fact, there are threads in here that discussed it quite extensively.. feel free to look it up..

in short, give it a few days.. my personal experience was about 7 working days and the system sorted out itself.. didn't do anything else (eg. re-register at ATM, etc).. all the OTP are properly received after

*provided u don't have any urgent financial transactions to make*