As we know nothing about your underlying offense, the terms of your probation, the required group meeting, or why you needed to attend that particular meeting, we're not in a position to comment on the probation officer's insistence that you attend that particular meeting. If there's something about these meetings or when they are scheduled that could potentially interfere with your job, by all means consult a lawyer about whether you should petition the court to modify your sentence, such as by allowing some form of alternative to the meetings.
As a general rule, probation officers want people who are on probation to be employed and to succeed in their jobs.

