Hey, not sure if Bitumen is new in PY but as it has no icon your mod dies:
496.514 Error MainLoop.cpp:1284: Exception at tick 3: The mod Resource Map Markers (0.3.5) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event sonaxaton-resource-map-markers::on_nth_tick(1)
sonaxaton-resource-map-markers/control.lua:408: bad argument #1 of 2 to 'ipairs' (table expected, got nil)
stack traceback:
[C]: in function 'ipairs'
sonaxaton-resource-map-markers/control.lua:408: in function 'get_resource_icon'
sonaxaton-resource-map-markers/control.lua:440: in function 'create_tag'
sonaxaton-resource-map-markers/control.lua:555: in function 'for_each'
sonaxaton-resource-map-markers/control.lua:271: in function 'patches_for_each'
sonaxaton-resource-map-markers/control.lua:543: in function 'show_tags'
sonaxaton-resource-map-markers/control.lua:878: in function <sonaxaton-resource-map-markers/control.lua:769>
Would you like to add a handle for missing resource icons and just use a generic white dot or the Factorio\data\core\graphics\empty.png?
Cu, steinio