whats the biggest challenge you have faced with a client so far?

For me, the biggest challenge I faced with a client has been maintaining momentum for the implementation of PathMotion when the project manager on the client side left the business with short notice. Given that we were still in the planning phase, things changed quickly. Documentation had to be re-submitted and decisions on implementation were altered, amongst various other things. I had to introduce myself to the new stakeholders and engage them in the process. This unexpected change inevitably shook the momentum of the implementation process. I focused on this client during the transition period - but it was very challenging!