2 Answers

There are so many. 

1. Difference in pay for the same job depending on gender. 

2. Sexual harassment 

3. Denial of job due to gender.

4. One gender not accepting the authority of the opposite gender. Some men have issues with respecting a female boss. 

5. Female employees having normal health issues understood by their boss and maybe getting in trouble for taking time off monthly because of these "health issues". 

That's about all I can think of right now. 

gender refers to male and female....men and women.....boys and girls
issues would be topics of dispute
gender issues would be topics of dispute between men and women in the workplace.
Some issues could be dress code, salary discrepancies, harassment policies, management opportunities, supervisorial positions, partnership opportunities....anything where the difference in sex could be construed as having an outcome on any of the issues I've mentioned.  
I'm sure there are many more.....this is barely scratching the surface.