Endnote library conversion to 9.3 or 20 from x9 missing references

I’ve downloaded X9.3 and also tried X20 (don’t like the format), and tried to convert my library to the new format. 

The conversion has changed tonnes of references and is missing hundreds of references. My original endnote library has 2740 references, the converted library has 2222 refereces, there does not appear to be any specific reason why those references that are missing did not transfer over and many of the corrections I made to the library (changing from capitals to lowercase in titles) have reverted back to their old incorrect formats. 

I don’t have time to find all the missing references again and fix all the references I altered before. Why would any sane person without a month to fix their library update to X9.3?