Did you try the advice here?
https://community.48.ie/t5/The-Knowledgebase/The-Roaming-Troubleshooting-Guide/ta-p/52179
If that doesn't work then you'll have to contact 48 support.
See the link in my signature below or email them at support@48months.zendesk.com
But bear in mind that many people have been having problems with roaming lately and many never get it working at all.
And 48 themselves have admitted that there are problems that may not be sorted until later in the year.
