Your comments

Thank you very much. let me know if there's anything I can help you with. 

oh sorry! the order number is 5772610491429 . Thanks . 

Hi, can I just confirm that I am requesting a refund? I can't find any information on how to do so, so I believe it has to be done manually?

Thanks for the reply. I understand your position, I have also released assets on the store that did not do as well as I expected. I don't envy you having a code asset since i can imagine support for that is much more difficult and involved than for a simple set of models. 
I wish you all the best!

I'm sorry I can't deal with this. There are too many issues with the asset pack, I can't afford to be spending this kind of time trying to get this to work. I appreciate you taking your time to help with this, but I have to draw the line somewhere. If it's advertised as working for 2017, then it should be working and I shouldn't be having this much hassle. I'm going to leave a review and request a refund. people should know that A, you are dedicated to helping address issues, and B there are potentially a lot of bad issues. I hope you can resolve everything with it and i wish you success, but this is the end of the line for me. 

Also, is it supposed to take over 12 hours to upgrade the prefabs? I've got about 600 trees but I don't understand why it would take this long. I could manually replace them faster.

never mind, that divide by zero editor is the same as before, but I thought this was what was happening because there is a compile error somewhere. I'm reverting to the 2017 version, editing the code that you posted above, and then once my trees are built, if it does not display then i will try importing the scripts you sent me in google drive. hopefully everything wil display correctly, but I am worried about this compile error. if I open the tree converter things might go crazy. 

well now it's got a divide by zero error on the tree converter script before i even try to run anything.
I don't have much patience for this, I'm going to focus on upgrading my project to 2018.

now it all appears to be working!  fingers crossed! 
I put my tree in the gaia scene with the new scripts and everything and it behaves correctly. I'm sure i can probably benefit from reconverting it along with all my other trees, but for the most part this all seems to be a success. thank you.

very weird.  I believe it seemed to work correctly in your scene. I cam back to my scene and now it's being really inconsistent. when i selected billboard only, it shows both the billboard and the full model at the same time.  now i set it to a long lod, and it transitioned correctly, but as i was moving the camera closer, it retained the billboard quite stubbornly until I was right next to the tree.