loadgraph fails with DOT format

I can save my metagraph with savegraph but cannot load it with loadgraph:

using Graphs,MetaGraphsNext

complicated = MetaGraph(DiGraph(),
                   VertexData = Dict{Symbol, Int},
                   EdgeData = Dict{Symbol, Int},
                   graph_data = (tagged = true,)
               );

complicated[:a] = Dict(:code_1 => 1, :code_2 => 2);
complicated[:b] = Dict(:code => 2);
complicated[:a, :b] = Dict(:code => 12);

savegraph("mwe",complicated,DOTFormat())
loadgraph("mwe",DOTFormat())

Raises and error message:

ERROR: MethodError: no method matching loadgraph(::IOStream, ::String, ::DOTFormat)

Any ideas how to solve this?

Start by reproducing the supplied MetaGraphsNext example with savegraph("mwe", complicated, DOTFormat()) and loadgraph("mwe", DOTFormat()). Inspect the savegraph and loadgraph method definitions and their DOTFormat handling. Done means the example loads the saved graph without the reported MethodError.