There are several reasons why a client may not respond to a proposal on Upwork. One reason could be poor English communication skills. If English is not the freelancer's first language, they may have difficulty conveying their ideas and proposals in a clear and concise manner. This can lead to a lack of response from clients who may not understand the proposal or may not feel confident in the freelancer's ability to communicate effectively. Another reason for a lack of response could be the freelancer's lack of experience. Many clients prefer to hire freelancers with a proven track record of completing successful projects, and may be hesitant to hire someone who is new to the platform. Additionally, the sheer volume of proposals that clients receive can also be a factor. If a job posting receives a large number of proposals, it may be difficult for the client to review them all, and they may choose to only respond to a select few. Finally, a proposal that is too focused on the freelancer's needs and not the client's needs may also be rejected. It's important for freelancers to make sure their proposals are tailored to the specific needs of the client and clearly demonstrate how they can add value to the project.