Strange experience in R&D / Research assistant post. Is this a red flag?
First of all, your supervisor should be principally responsible for accounting for funding. The brunt of reporting the results for funding purposes is not on your shoulders. (This does not mean that you will not be asked to help in the reporting process). 

Because it is hard for us to know what the parameters of your position and funding are, it is relatively difficult to gauge what types of results you were supposed to get and/or report on. Surely you documented the work that you did on the project? Can your own/your professor's actual work not be reported on? Simply report what you did to the funding agency. Joint ventures can be messy and academia and industry focus on different work strategies and outcomes. Report to the funding agency what your end did on the project. That is what they will be looking for. You either produced results and work or you did not. That is what the funding agency will likely care about. 

Based on my topical understanding of your situation, it sounds like you participated in a joint venture with an industry partner and they developed a solution independently from you. Are they contesting that you helped? Are they part of your funding? Not knowing these aspects of the arrangement and outcomes, it is difficult for me to provide specific guidance on any issues that may arise from such an arrangement.



As a piece of holistic advise for future research with industry partners, make sure that there are actual detailed contracts produced before engaging in any joint research. (This may not be your duty as a research assistant, of course). If you professor does not have any sort of contract, communications, or documentation of your joint work with the industry partner then he muffed pretty badly here. (Although, again, as an RA, this in not your job and you should not really be blamed for possible failures on the part of your supervisor). 

Ultimately, this situation sounds like it may be your professor's job to lead the way in handling legal and reporting outcomes. No quality professor will throw the legalities and finances of a joint venture project at the feet of a research assistant.