BEx Report Designer GUI 7.5 Issue

I have recently installed GUI 7.5. I then used it change an existing BEx Report Designer Report. Having done so it instantly gave me an error when I tried to run the report as a PDF e.g. Print Version. I get the error:

No access to data provider or data provider does not exist

Cannot access data provider DP_1; it does not exist or cannot be read

I can no longer add in a query to a new report either.

Before moving to GUI 7.5 I had no issues at all.

I have no removed GUI 7.5 and reverted to 7.4 and re-saved it again and the issue is resolved. Is there some additional requirements to be able to use GUI 7.5?

Thanks

Joel