Adobe Acrobat Cloud stuck on Prepare responding when requesting e-signatures

Have a Adobe Acrobat Pro subscription which includes PDF and e-signing tools, woking on Cloud  relevant instructions are.
Click Request e-signatures, gets to Add (as below) where i specify recipient (and it searches my Email contacts correctly).
Click Specify Whete to Sign and it moves to Prepare

It is stuck on Prepare, never moves forward. Tried Windows/Linux on Firefox/Chrome to same affect, so seems to be unlikely browser related. Alos tried different documents, again same effect. Am logging into Adobe with Google authentication.