What type of irreconcilable differences might exist between an attorney and client to cause the attorney to withdraw from a divorce case? Is this code language for not paying attorney fees or is it used for a wide range of possible attorney-client difficulties?
Comments here and here suggest that "irreconcilable differences" can be used to explain "withdrawal when the client fails to compensate the attorney", but it can mean many other things. The point of the phrase is to not divulge the reason.
Amidst the various scenarios discussed under Rule 1.16(b), subsections (3) and (4) permit withdrawal when the client fails to compensate the attorney [...]
When it comes time for an attorney to prepare the motion for withdrawal for such reasons, however, [...] an attorney may consider citing the ubiquitous “irreconcilable differences” in the motion to withdraw, rather than divulging pernicious information about the client.
However, it can mean many other things as well. The point of the phrase is to not divulge the reason for withdrawal.
Don't assume that it is "code" for anything in particular: it just means that they can't work together for any number of reasons.
Perhaps it is a dispute about money, perhaps it is a professional disagreement (i.e. The client won't agree with the professional advice) or perhaps it is personal (i.e. They hate each other).