Problems with role-based discounts

Kind regards.

First of all, thank you for this very useful plugin.

Secondly, I have the following problem. I am using the discount rule based on a specific role, but sometimes the discount is shown on some products but not on all, other times it is shown normally.

* I have already cleared the Siteground plugin cache.

* I have already cleared the cache from Siteground’s Sitetools.