Hello Marat, believe it or not I tried to save a mission in my 4.12 with SAS ModAct 5.30 and I have the same issue as you.
I can add the object irrespective of which of those two entries I use.
The objects themselves are by Uufflakke, I think a re-paint of Cannon objects, and I have that pack as well as the objects packs from Boomer.
The map alterations I made were originally in my DBW install and in that missions do save, the QMB missions I made would have been done in DBW and do play in my 4.12 install even though the map will not save.
I would think that as long as you have the object in your install in the folder called up by the static all should be good, unless it can be blocked some way, however, as you and I can place the church on the map in FMB that cannot be the case surely.
This is a strange one and the particular object is/has been a problem on various maps.
Not sure really what I can suggest, maybe someone else has a idea.
I did try adding the map again with the various fixes but no go.
Wishing you all the very best, Pete.