First click to blog title does not open the blog article

I notice when visiting my blog https://www.datanumen.com/blogs/ via iPhone. Sometimes the first click to the blog title, such as 11 methods to fix..., will not open the blog article. I need to click for the 2nd time, to be able to bring out the blog article.

I have used Lamdatest real devices to make the tests, and below are the results:

1. In Canada, Australia. The click will always bring out the article body.
2. In US. The problem will occur, but not very frequently.
3. In Israel, Kuwait. The problem will always occur.

So, I just wonder whether the issue comes with the blog theme, or the server, or the CDN(I am using Cloudflare CDN), or the mobile phone device, or the mobile service provider?

Thanks