blueprint downgrade removes recipe

so i noticed when i started a new game and have not researched assembly 2 thats in my blueprint it losses the recipe selected because it got downgraded

thats expected behaviour, the recipe would only be available in Assembly 2 and higher.
It also doesn't load the recipe if you haven't unlocked the tech.

I think it was configured like that to prevent blueprints giving access to recipes you shouldn't have access to.

If you're making blueprints you need to take that into account

it just seemed wrong since it removed the lab equipment from the assembler but when downgrading the basic construction parts and electronics and mechanical parts they all got removed

I'd double check the specific recipe, it may be a legit bug.
The basic construction parts has a Steel alternate recipe, IIRC that one requires a higher tier assembler

So, I stumbled across this issue and did some investigation. I created a blueprint with an Assembly V with all recipes active and planted it in a game where I only have Assembly III unlocked. The result was that the following recipes were retained (but downgraded to 25% capacity, as expected):

• PCB
• Houshold Goods
• VP1, VP2
• LE1, 2, and 3

The following recipes, that are available on the Assembly III and active in the Assembly V blueprint (albeit at 400% of the capacity), were inactive in the planted Assembly III:

• Construction Parts I, II, and III
• Mechanical Parts (both from Steel and Iron)
• Electronics I, and II

My expectation would be that all the recipes mentioned become active when the blueprint is placed. The auto-downgrade feature for blueprints is great, but with this issue the value of it is diminished somewhat when the recipes don't follow along reliably.

I also did a test to see if recipes would be upgraded properly from Assembly I to Assembly V, and all the recipes that are possible in the Assembly I (CP1/2, MP, VP1, E1) follow along when the Assembly is upgraded, all the way to Assembly V. Result was that they were all upgraded properly.

In addition, the same recipes also downgrade properly when the blueprint if the Assembly V is copied with the copy command and then downgraded using ctrl-scroll or the downgrade button, so it's JUST when it's forcibly downgraded due to lacking technology that the recipes vanish.

My TL;DR summary: it's a bug

similar: Some recipes disappear when BPs downgrade buildings