Overlapping nodes with neato and some fixed nodes

I'm trying to create a layout for a graph where a few nodes have fixed positions and most nodes don't. The output for nodes with fixed positions is correct but the remaining nodes seem to be laid out completely ignoring the fixed nodes (Overlapping nodes and edges). Is this the expected behaviour or am I missing something that would make the layout algorithm incorporate fixed nodes properly?
I'm haven't set any attributes besides the nodes' width, height and pos (with "!", only set on fixed nodes), all other graph, node and edge attributes are unchanged from their default values.

Any help would be greatly appreciated
Thanks and best regards
Michael

Overlapping nodes with neato

To avoid node overlap, you need to set overlap=false in the graph. Unfortunately, all of the current node overlap removal algorithms in Graphviz assume all nodes can be repositioned.

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