I cannot see your WSDL so am baseing this on what I imagine could be the issue(s).
Firstly, opening the WSDL in a browser might be OK since, the browser may interpret the WSDL as HTML, rather than XML and therefore not validate it for correctness. If is in your WSDL, that is valid HTML, but not XML. SoapUI is certainly having trouble parsing the WSDL content as standard XML judging by the error.
Also it may be possible that your WSDL imports XSDs that allow the use of nbsp to be valid, sometimes the schemaLocations of these XSDs may be unavailable to SoapUI e.g. if they require proxy settings to be confgured in order to download the XSDs.
I hope this makes some sense and isn't too off-beam? Like I say I can't see the WSDL, so cannot inspect or test it etc.
Well, possibly the tools you mentioned, esecially the online ones may have acces to the imported XSDs.
I think you can attach files like this to forum posts. I have personally never tried, but have noticed other people attaching files. Please feel free to send the file.
Don't worry, I don't work for SoapUI, and even if I did I am sure I wouldn't have any problem accepting the possibility that it could be a SoapUI bug 🙂 - Its just that in this case I was hopefull it might be a separate issue, like the proxy etc. Also the SOAP/WSDL code is relatively old I think and I have been able to test complex WSDLs in the past. Could still be a new bug though...
If you send your WSDL I will have a go importing it and see if I can suggest anyting further, apart from SoapUI proxy setting etc.