The normal concrete mixer is working well. Just the Electical isn't.
Hm let me give it a shot but keep looking in to it. Until the use the hand cranked one
Sorry, i forgot to register "WorkGiverDef" to electric mixer

Just copy near with simple electric mixer workgiverdef. into Industrialisation_SK/Defs/WorkGiverDefs/COWorkGivers.xml
they differ only by the letter "E" "EMixconcrete"
<WorkGiverDef>
<defName>DoBillsEMixconcrete</defName>
<giverClass>WorkGiver_DoBill</giverClass>
<workType>Crafting</workType>
<singleBillGiverDef>EConcreteMixer</singleBillGiverDef>
<verb>mix</verb>
<gerund>mixing</gerund>
<requiredCapacities>
<li>Manipulation</li>
</requiredCapacities>
</WorkGiverDef>