A big problem i see liberals having when trying to change the minds of both leftists and conservatives, is an inability to even consider any aspect of another’s perspective, and a belief in one’s own perceptions as objective reality. In doing so, they will argue against their perception of others beliefs, rather than actually discussing and finding what those beliefs are, or where those beliefs come from.

I've noticed this a lot, but mainly on the internet, especially with people that I have either a more distant social connection with or none whatsoever. It's especially visible when talking about guns, since that's a subject where the average conservative is significantly more well-informed than the average liberal (I say this as a leftist, not a conservative). The liberals that engage in these arguments seem to be fully convinced that they are in fact more informed, even though they tend to have an active aversion to guns, rather than an interest that would motivate them to learn more.

In-person results are better. There's a level of politeness that comes with interacting face to face, plus some level of mutual respect and trust that comes with social connections. I've managed to significantly shift the opinions of a number of my friends on the subject. I could be in a bit of a left libertarian-leaning bubble, though. The current cultural climate is probably also significant. The threat of an active fascist movement in the US is a pretty decent motivator. A very large portion of liberal internet commentators seem to be unmoved, though.