The Realo/Fundi and class/identity splits do not overlap; they are the x- and y-axes on a graph. It is perfectly possible for candidates to land in any of the four quadrants. That said, Fundi positions tend to line up with class on economic and welfare state issues, but with identity on social justice issues.
Immigration is a good example of the latter. The Fundi position on immigration (i.e., to abolish ICE and have essentially open borders; anything else is racism) is completely associated with identity, and is diametrically opposed to the interests of the class group, many of whom believe, as Trump does, that immigrants depress wages and steal the jobs of the white working class. Bernie Sanders, to cite one prominent example, has said that open borders are a Koch brothers fantasy.
The Fundis will find that open borders may sound great to immigration activists, but not to the vast majority of Democratic voters, let alone the entire American voting public. It’s electoral suicide. One has to hope that the Realo position of enforcing the law, but working for a compromise that provides a reasonable path to citizenship and a landing place for genuine refugees, will prevail in the primaries.
The Realos almost prevailed during the Obama years, since all of the GOP factions except the Reactionaries are open to reform. The problem was timing; by the time the immigration bill passed the Senate, the GOP controlled the House, and the Hastert Rule prevented a vote on the Senate compromise. It is perfectly possible that a similar bill could get through the system after 2020 if the Democrats have control of both houses.