Hi,
Source address persistence should not result in one member receiving all traffic unless there is an upstream device that does source address translation and masks the actual client IP or -most likely- you are using a wide mask (0.0.0.0) in the source address persistence profile, which is the default if you choose none for the mask field. You may need to narrow this mask to something like 255.255.255.255 to have a unique persistence entry for each /32 address.
Also check this: https://cdn.f5.com/product/bugtracker/ID752933.html