Conditional Formatting Working For Some Users And Not Others

I have set up a basic sheet for a colleague, whereby the Team Leader can enter client names into a control sheet, and then the team can add the client names into the allocations sheet when they take on the care for that client, and Conditional Formatting colour codes the cells to show which program a client comes under.

My problem is, the conditional formatting works perfectly on my computer, and another colleague's computer, but for two other colleagues, only half of the colour coding works... leaving half of the clients cells white, indicating they are not allocated to a program.

I have checked that we are all using the same network pathway, macro security settings etc.