cannot close nvui if there is another program called from nvui is not closed

[xarthurx]

I write latex in nvim using VimTex.
There is a function to call pdfviewer (SumatraPdf in my case) directlly from nvim, and do live compiling.

For other nvim frontend, I can close nvim and leave the pdf viewer open.
In nvui, closing the nvui window will freeze the ui, until I close the pdf viewer (after that nvui will close automatically).

Ideally, this should not happen.