The latch mechanism on the Mesa car seat does not engage with the base. The latch is stuck and will not budge. The car seat is unable to be used with the base because it is not locked into the seat and posing a risk of ejection. The customer service of UPPABaby has been a constant dead end and they do not want to provide a solution to the issue. This tells me that UPPABaby does not care about the safety of the children riding in their car seats