Slab edge not joining

[jason_crossVTGU8]

created using dummy floors to emulate wall footings

At my office, we have been using solely the architectural linked model and filters to create our structural plans.  For our wall footings and slab edges, I will copy or create a floor and use the slab edge tool to make both the edges and wall footings (open to suggestions on other means, while we're on the subject).  When trying to get them joined, they will join in some situations but not others and I can't figure out what is the determining factor.  The conditions appear to be the same to me, but I must be missing something. The yellow indicates where I'll create a dummy floor to make the WF. The above photo shows them not joining properly, and I don't want to use the linework tool on these multifamily projects, too time consuming as is.  The below photo shows same families and conditions but they join properly, go figure

proper join

[jay_colcombe]

It may just be due to small edges or returns, and the Slab Edge cannot be created correctly as there is insufficient length to create the profile shape extrusion?

Just below the Yellow highlight the wall steps nominally and could be the cause unlike the mirrored wall opposite which shows as expected.

I would personally create the Wall Foundations as Foundation Walls in my Structural Model as when investigating it would be as expected and try to avoid workarounds to make things look like something else!  This also has benefits for tagging and schedules etc. if needed. 

There is a Foundation Wall Style/Type which only goes downwards which makes the process much easier to implement