Sitemap Generator Keep Displaying Loading Bar

Hi,

Currently I'm using Sitefinity 8.2.5900.0.

I tried to generate sitemap.xml using sitemap generator.

I set sitemap generation mode to manual.

After I clicked Generate Sitemap,  the loading bar appeared but it stuck at 5%, Step 7 of 7 : Writing sitemap file (please refer to file attached).

But when I accessed  /sitemap/sitemap-index.xml and /sitemap/sitemap.xml, the sitemap.xml and sitemap-index.xml file can be downloaded and the date written in sitemap-index.xml is correct.

How can I fix this ?

Thank you.