Sometimes it happens, Flow can’t find a Form you created. I find this happens the most when you have just created a new form, however I’ve had other forms just not show up.
I don’t know why this happens. If you really want to resolve it, contact Microsoft support. I guess it’s a caching/timing thing between Power Automate and Forms, but again, I’ve seen older forms not show up, so really I have no idea.
Workaround: Force Flow to use your Form
So let’s force your flow to love your form. Let’s start in your form. Go in and edit your form. Note the URL in the address bar of your browser. You’ll see something like
.../DesignPage.aspx#FormId=KFG....C4u. You want to copy the value after
FormId=, it’s a long ID, make sure to grab it all.
Let’s go to Power Automate and hop into your flow. In your trigger or action, select Enter custom value at the bottom of the pick list, and then paste in the previously copied form id.
That should do it! Pretty easy and it works really well. You may notice later on that the ID will be replaced by your form name, Flow eventually realizes the error of its ways.