I was facing the same problem. The problem was I did not enter my phone number. After entering the phone number the problem gone. Just check your profile and fill the missing field.
Could you please try clearing your cache and cookies or use a different browser? If that doesn't help, please let us know so we can assist you further. Thank you!
I checked your account but was not able to replicate the problem. Could you please log out and then log in again to try and submit a proposal? If you`re still experiencing the same problem after this, let me know here. Thank you.