1.14 silly mission

[Trin Tragula]

Yes it'll be fixed for next patch. The range check was accidentally removed.

 

[Trin Tragula]

And why as Muscovy I keep getting Subjugate Kazan AND Subjugate Crimea at the same time, which effectively leaves me with just one mission? Where are those regarding HRE (before you ask: I'm Catholic and the Emperor) and many others?

It works like this:
Missions come in 3 varieties, ADM, MIL and DIP.
Normally the game will try to display one of each. If one category has no alternatives available to you it will display 2 or 3 of the same category rather than make the list shorter. Having just 2 missions available when there is a whole bunch of missions still valid in another category would be pretty frustrating after all.

Missions can be unavailable either because they don't fit you current situation or because they are blocked for some other reason. Reasons include if you already have the mission reward active (a timed modifier most of the time) and some missions are only ever available before you have completed them successfully once per game (these fill more of a tutorial function, the standard "get an alliance" mission is one of these). There are also some which cannot repeat unless a certain time has past since you last completed them (improve relations with elector is one of these, it cannot retrigger unless 20 years has past since you last completed it). The game will also not show the mission you had immediately before again unless you have another mission in between.
As there are a lot more military missions in the game than the other categories the chance of them running out is the lowest and that's why when multiple missions of the same type are displayed they are the most common.

In your case you get to pick from 2 MIL missions at the same time because there are either no ADM missions or no DIP missions for which you are eligible. They should not really be reducing your number of options as you only get two of them due to lack of other available missions.