Retention package FMLA

My company is located in California. Some employees including me were provided a retention bonus during org restructuring and the company provided me the retention bonus as long as I will be actively employed for nine months at a satisfactory performance level. After nine months, my employment will be terminated. The retention bonus will be paid in a lump sum on the last day of the nine months. However, I will be on maternity leave starting from the seventh month during the nine month period. Normally the materiality leave would last more than 3 month which means I will be on FMLA leave when my employment relationship get terminated. I wonder whether being on maternity leave would impact my eligibility to obtain the retention bonus on the last day of the nine month period? The wording “actively employed” was not cleared defined in the retention bonus letter. Will FMLA provide me some protection? I do not think the other employees would not take any PTO during the nine month period. If other employees take paid vacation during the nine month period, I think they would still get the retention bonus on the last day, thus it does not seem to be reasonable if company refuse to provide me the retention bonus just because I am on FMLA leave.