If you are using the "LiteSpeed" plugin, you may encounter some issues with the upsell page when running the funnel pages. This is due to aggressive page caching (which is a good thing!), but it can be easily resolved by excluding the offer page URI from the cache plugin.
You need to exclude offer pages by following these instructions:
Step 1: Note down the slug of your offer page from the general settings:
Step 2: Open the settings of "LiteSpeed Cache"
Step 3: Jump on the “Exclude” tab.
Step 4: Scroll down this page and locate for "Do Not Cache URIs"
Step 5: To exclude “offer” pages enter your noted offer page slug (from step 1) with special characters as shown in the screenshot: “/offer/”
Step 6: Scroll down the page and click on the "Save Changes" button to update the settings.
By default, theupsell offer page slug is "offer". If you had changed the offer pages slug for any reason get the slug from WooFunnels > Settings > General > Permalinks.