Thanks for your help today.
After a lot of flitting between 2 pc’s, one with v4 and one with v8 I found a missing label on the v8 version. Per chance it had its hidden property set to TRUE. It must have been there for years as it was an old debugging label and not referenced anywhere in the project so I deleted it.
Copied the project to 2’nd PC and opened it in v8. Form converted correctly. Ran in Chrome and itial testing looks good. I hope this information might help you in the future.
Thank you. John