Custom node saving deficiency

Dear Dynamo saviours,
Let’s try to explain my problem. I’ve created a custom node and published it locally to some location. I open it through the project, edit it and save it. It works fine for several opening and closing times and then, at some other point, when I reopen the .dyn file which contains the custom node, the node is not still loaded (img 1)

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So I find its location and try to reload it (img 2)

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What appears is the .dyn project and nothing close to the custom node (.dyf file) I had saved and published previously. I also do not seem to find a way to recover the original .dyf file. I really don’t know what causes it but it is the third time it happens and causes me huge trouble every time. The only thing I suspect is that when I have both the .dyn file and the .DYF file open and try to save the .DYF it saves the .dyn instead. But is this normal? PLEASE HELP