Fix WPUpsell Visibility

I’ve just finished installing and configuring the WPUpsell plugin on my WooCommerce store and have already built a post-purchase campaign. The campaign technically “activates,” yet nothing appears on the site once a customer completes the checkout. It should display right after the checkout page but before the standard thank-you screen. My checkout flow runs on WooCommerce defaults with only a few light template tweaks, so the issue feels more like a hook or compatibility conflict than a heavy theme override.

Here’s what I need:
• Diagnose why the activated campaign is invisible on the frontend.
• Adjust any hooks, template overrides, or plugin settings so the offer reliably shows in the intended post-checkout spot.
• Leave clear notes on what you changed so future automations I plan won’t break your fix.

Please be comfortable digging into WooCommerce, WordPress hooks, PHP, and the WPUpsell dashboard. Once this is squared away, I have a queue of further payment-flow automation projects, so a clean, well-documented solution here could turn into steady work.