Hi - No problem with your file just lack of knowledge to the manufacturers your sending to. No problem with part as solid exporting as step is common practice I do it all the time. I design many parts as sheetmetal in MOI then convert in SW for output. When importing into SW need to convert the part into sheetmetal. Here are files for you to send back to your manufacturers.

Here is a project I just completed last week all sheetmetal designed in MOI then output for manufacture in SW2018.