Ahh I feel your pain. This word may be your product's greatest strength and yet its greatest weakness -> Enterprise.
I can realise where your customer is coming from. The data you want to collect is pretty harmless for regular consumers as long as its anonymized. But for enterprises, you are asking them to share how they operate your software potentially leaking Secretive Business Practice! We faced a similar situation when our product was being used by a Government Entity and any sort of analytics information meant Tax Default data of Fortune 500 companies!!!
You could talk to your customer but do remember a key point. The person in your client organisation with whom you have a relationship with is almost in all cases a non user of your software. This can be a C-Level Executive or the Purchasing Head or Dept. Head etc. So to be effective you have to break channels and heirarchy, you have to be talking to Data Entry operators / Clerks / Engineers who actually use it. This could work out in your favour as they would probably ignore the above point. Your sales team would have to reach out till them though. We had a chat with them during training sessions and reviews and we got very very useful feedback.
Incase your customer doesn't mind sharing data. I wouldn't advice paying them. You are doing this after all to improve your product's usability which in turn is going to increase your client's efficiency.
My suggestion to you would be to not collect analytics data for your app in production but to have a separate team / set of consultants use your product the way your end customers would and collect analytics data from there. It may not be 100% accurate data but it is certainly data which you can use.