In my logs I'm seeing a flood of messages like these:

Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (3, -1)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (-6, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (-5, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (-6, 1)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (-4, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (-3, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (-3, 1)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (-2, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (-1, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (0, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (1, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (0, 1)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (2, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (3, 1)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (3, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (4, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: fast-transport-belt[fast-transport-belt] at (5, 0)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: assembling-machine-2[assembling-machine-2] at(-5, 3)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: assembling-machine-2[assembling-machine-2] at(-2, 3)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: assembling-machine-2[assembling-machine-2] at(1, 3)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: assembling-machine-2[assembling-machine-2] at(4, 3)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (-4, 5)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (-1, 5)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (2, 5)
Script @__MathCoProcessor__/tag_support.lua:155: ERROR: map entity not found in blueprint: red-inserter[red-inserter] at (5, 5)

This is on Factorio version 1.1.12 and MathCoprocessor version 4.1.0

Sorry for the delay.
I guess it has to do something with blueprints. The first time I wrote an that an entity storing data (kind of the operation) to store within blueprints I found nothing similiar how other have implemented this stuff.
A fast solution might looking for a blueprint with the combinator an delete and recreate it.
Maybe there is a better solution with factorio 1.1 but have currently spare of time :(

I still could not reproduce these logs.
But due to refactoring the blueprint handling, the behavior does not belong to you.