I think the incompatibility arises from how each ideology defines property. Canarchy advocates for extremely strong property rights. I'm not to sure about Sanarchy, it seems that they vary from weak property rights to no property rights. Nonetheless, this has the effect of completely changing how each society will function. One is where control is defined by 'capital' and the other is based somewhat on 'public opinion'. If I own all the capital then I can do whatever I want with it. Compared with; if I misuse my capital, others can take it from me despite having no prior 'right' to it.
An interesting consequence in the various views of property rights (in Sanarchy) is that the end result of some versions of Sanarchy is very similer to what a Canarchist would want. All versions of Canarchy allow groups to from socialised communes if they buy the property first. Only a number of Sanarchists, I think a minority, would allow capitalists to do the same. That number would allow communes, if they democratically voted, to form a hirachal system with uneven division of resources, with money, investment, savings, hiring other people and so on.
A typical Ancap would expect the capitalist communes to outcompete and eventually become the majority anyway. Creating the same result which he originally wanted.