I'll add one that even after 200 comments I don't see: Failure to explain the reason
why. Coming down to their developer with a list of tasks without explaining why those tasks are the most important and will lead to company success.
You might think startups are small enough that this couldn't happen but that was actually where my worst experience was. The founders are visibly in a meeting with a couple people, maybe "suits", maybe not. They come out of the meeting and the next day your priorities are rewritten. Cool beans, that's a thing that can happen and that's not my issue. My issue is, why? What are the goals we are trying to hit now? What's the plan? Why is that better than the old plan?
This is especially important IMHO for more senior engineers responsible for architecture and stuff, because those matters can greatly affect the architecture. Telling me why lets me start getting a grasp on what parts of the code are long term and what can be considered a short term hack, what the scaling levels I need to shoot for, and all sorts of other things that are very hard to determine if you just come to me with "And actually, our customers need a new widget to frozzle the frobazz now more than they need to dopple the dipple now."
Not necessarily the biggest issue, there's a lot of other suggestions here that are probably bigger in most places, but this is one that has frustrated me.
(I'll also say this is one you may be able to help fix yourself, simply by asking. If you are in that senior role I think you pretty much have a professional obligation to ask, and I would not be shy about working that into the conversation one way or another.)