Lazy loading, a technique in web application optimization, involves loading content such as images only when the user is likely to need to see them. This method can significantly improve page performance by reducing the number of requests to the server and the overall volume of data transferred during the initial page load. However, despite its benefits, lazy loading can also bring forth a number of issues that need to be addressed.

User Experience Problems
One of the main issues associated with lazy loading is the potential negative impact on user experience. If the technique is not implemented correctly, users may encounter moments where instead of images, they see only blank spaces or placeholders. This delay in loading can be frustrating and lead users to abandon the page.

SEO Challenges
For search engines, indexing content that is loaded lazily can be challenging. If a search engine crawler doesn't encounter images during its initial crawl of the page, those images may not be included in search results. This can have a negative impact on SEO and the visibility of the page on the internet.

Technical Hurdles
Implementing lazy loading requires proper technical solutions. Errors in the code can cause images not to load correctly or at all. Compatibility with various browsers and devices is another factor to consider. Older browsers may not support lazy loading, necessitating the implementation of polyfills or alternative solutions.

Testing Complexity
Testing functionalities like lazy loading can be complex because various factors need to be considered, such as internet connection speed and user scrolling behavior. Ensuring that images are loaded at the right time and without issues across different devices and browsers requires thorough testing.

While lazy loading offers numerous advantages, it's important to be aware of its potential issues and challenges. Proper implementation, testing, and optimization are key to harnessing all the benefits this technique offers while minimizing its negative impact on user experience and SEO. Understanding these challenges and seeking effective solutions can help developers leverage lazy loading more effectively for faster and more user-friendly web applications.