Lost highlights from book - how to recover?

I read a book for a university course. I was thorough with highlighting and classifying highlights... The book is 177 pages long and only 36 pages worth of highlighting was saved. 

Why do this happen? Why is it unecessarily hard to come in contact with support to fix this? 

I cannot recover earlier versions of the highlight file... And there is only one - the 'broken' one.. 

Is there other options or is HOURS of work gone for good? 

Seeing this issue dating back to 2015 makes me really annoyed with Adobe... It should not be an issue 9 years later.