I know nothing about those claimed locker room issues, but I do know potential sources for such issues:
Totally unfair disciplining / punishment culture, stupid and unfair TOI and role/opportunity distribution.
Certain veterans seems to be simply untouchable by Maurice regardless how stupid penalties they take or how lazy they defend. Younger guys get punished harsly occasionally in comparison. That's unfairness that doesn't only affect those that got mistreated, but also those who were benefactors.
Certain line combinations are not touched even if they don't work at all for an extended period, like CSW was for 10+ games in the early season for example. Only thing Maurice did change was that he increased their TOI even more, which was absurd.
It would also help if Maurice takes some responsibility and doesn't just throw others under the bus. Also PoMo, do not promise increased TOI/role, if you end up with decreasing TOI/role. That doesn't exactly build trust.
From my recollection, Ehlers was the best fit on the first line but he never got back there regardless of his effort and results.
Laine was promised big minutes before this season started and it never materialized. He even started the season really good, but you can tell he was dejected that no matter what he did, we wasn't going to be rewarded.
Those are just the two examples that come to mind. They aren't completely about individual players either, it's about what is best for the team, and human nature.