bring the in house expert of the company with you next meeting ?

Based on everything you said, they don't want to hear it. Organizational Behavior 101: If you make the same mistake as everyone else, it's not your fault. If you stray from the herd and anything unrelated goes wrong, you get the blame.

"he doesn't know what he is talking about", "their cargo cult", " this felt completely surreal" - hopefully you don't use phrases like that while trying to make a convincing point. How important to the company is getting this decision right? What are the repercussions if the "wrong" decision is accepted?

@JoeStrazzere Of course I didn't. I explained why it's wrong and that we can't expect the benefits from the topic when we're changing the fundamentals. It won't have much impact on the company overall, but I will waste 1 to 2 hours every week with this topic while knowing that it's not providing any benefit, although it will also not cause harm besides wasting my time.

Sounds relatively mild then

is this software related ?

@PeteW It's more about the lost opportunity, because it would really help us if implemented correctly. Instead I have one more time wasting regular meeting.

@Chris - so perhaps your best discussion point is the additional time it will cost you. If they still choose the "wrong" path, it's time to stop arguing. Some hills are not worth dying on.

It's hard to evaluate this without knowing what the actual issue is. Some issues are more important than others, and the phrase "choose your battles wisely" comes to mind.

Hey Chris. If you feel like you are living in upside down land, don't worry, that's completely normal. Google 'groupthink' and you'll find out that this is just something that happens from time to time, even in the best teams.

I don't understand. On the one hand you write "By implementing this incorrectly we will not get any advantage but also no disadvantage" and "it will also not cause harm besides wasting my time" (and then I don't even understand why you're raising the issue) and on the other hand "it would really help us if implemented correctly". How would it help you? Just state that fact. Actual, tangible, pros and cons of each. Let them decide. Make sure those facts and your recommendation are on the record, so if someone later complains it can't hit back at you (but don't say "I told you so").

What stage of your career are you in?

+1 I've heard this described in a military context as "command intent" (CI), with the implication being that you simply can't go against it, and will be run over or out if you do. (i.e., boss's primary goal here is to get the wonky plan implemented, all other aspects are just implementation details, won't listen to outside voices, etc.) My sympathies.

I'm confused by this: "By implementing this incorrectly we will not get any advantage but also no disadvantage, but it's affecting my motivation." Is the "no disadvantage" part accurate? If so, it sounds like a matter of opinion, in which case I'd...let it go. Of course you might have to do that regardless. Sometimes you have to let people make the mistakes they've made up their minds to make. Though by the wording it's not 100% clear that they are making a true mistake. Could you confirm what you mean by "no disadvantage"?

I'm explicitly not telling the topic to avoid distractions. Then we have no way of determining whether you are correct or not. We're back to argument from authority - yours - that you are, in fact, correct.

@J... To discuss the topic would be off-topic for Workplace.SE and it would reduce focus of the question. So why should I do that? As mentioned I have checked multiple sources and discussed it with officially announced experts in my company. What else do you want?