Corporate world is a shit hole where the only thing that matter is the opinion of a decision level breaker (escalation point) .
I've had the obligatory interactions with a few backstabbing and/or passively aggressive teams, and when things eventually explode and work their way up the leadership chain (hopefully to someone with more sense), it's a quick knife through "you said / they said" to produce a written document from a meeting 3 months ago, where the assumptions you've been operating under were agreed to by the other team.
Obligatory: producing said doc in this context makes you an asshole, and is a nuclear escalation. But some (rare) times call for that.
(If it's a habit, you should probably reflect on yourself and/or find a healthier place to work)
They change technical designs or timelines slip?
My read was that a team didn't want to be bothered with something, but I was working on a corporate priority, so we set a meeting, hashed out, and agreed on how issues should be brought to them.
When something happened down the road, the agreed process was followed, and they (surprisingly stubbornly) claimed they weren't responsible and shouldn't be contacted for this issue.