On Tue, 10 Nov 2020, Sylvain Hubert wrote:
> Indeed. Thanks for the information!
> 
> For the record, this is how the problem is finally solved:
> 
>     \setuphead[section][after={\blank[sampage]}]
>     \begingroup\setupindenting[no]\dontleavehmode\startxtable …
> \stopxtable\endgroup

Unless you have other reasons to create a group, you can just use:

    \noindentation\dontleavehmode
    \startxtable
    ...
    \stopxtable

Aditya