If you are using the "WP Super Cache" plugin, you may encounter some issues with upsell page when running the funnels. 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 here
Step 2: Open the settings of “WP Super Cache” and click on the "Advanced" tab.
Step 3: Scroll down below to the section where we need to add the string for the offer pages.
Step 4: To exclude "offer" pages enter your noted offer page slug (from step 1) with special characters as shown in the screenshot: "/offer/"
Step 5: Click on "Save Strings"
By default, the upsell offer pages slug is "offer". If you had changed the offer pages slug for any reason get the slug from WooFunnels > Settings > General > Permalinks