Hi, because our masts are bottom mounted and reinforced internally there is much less bend in the mast at that point. Sometimes the sail requires a hand slap in really light conditions or when your stopped to get them to change sides/pop through. (while sheeting in.)
Unlike windsurfers we cant pump the boom to get the cambers to pop through.
You may have a damaged camber or the end of the batten is actually snapped off. ( Due to the cams not being removed properly, in our case with tension still on the sheet rope, or windsurfers releasing the downhaul too far too quickly ) They ping off hard smashing something.

I've fixed a few on my second hand sails. Some "Severn" sails are a pain as the batten tip is stitched in.
To set up, rig your sail and pull
only the sheet rope (NO DOWNHAUL) hard till the mast bends into the front of the sails mast pocket. The mast will be laying on top of all the battens before you add sheet tension. The cams will then simply pop onto the mast if you get this sheet rope tension correct. If they wont slip into their positions easily then the sheet tension isn't right. With experience you will work out how much tension is required to clip/unclip them.

Fit cams by pushing down on the rear of the camber hard with your hand through the zip opening while lifting the front rollers onto the mast using your other thumb over the mast as a fulcrum outside the mast pocket. With the "correct" sheet tension they simply pop on. Much swearing happens till this correct tension is established!!
WARNING If adjusting batten tension.
If the batten tension is not simply adjusted with an allen key, then it is a good idea to back off your downhaul (While still sheeted in) and remove the cams from the mast
before undoing the batten tensioner end, as there can be a huge tension on the plastic "over centred" adjustment levers and if they are aged a bit/brittle they snap off. They are not easy to replace as unstitching is involved and a new one fitted to the dyneema cord and then all restitched. Cambered battens have lots of tension which removes all the wrinkles along the batten pocket/sail.
When de-rigging,
ALWAYS tie your sheet rope with a bit of tension and then relax the downhaul totally and then just pop the cams off easilly.
A cambered sail "sometimes" likes a firm outhaul because our boom is much lower than when windsurfing. So try that too. If the outhaul clew/eyelet is up from the bottom of the sail don't be afraid to take your boom up to it and overlap the boom with the sail as it makes very little difference when sailing. We sew on a re-enforced triangle with a new clew to keep it all neat.
More downhaul usually helps the cambers to change sides/pop through, but if this still doesn't work (and seeing that the other cambers are changing sides easily) I would certainly go ahead and ease of the batten tension. The bottom batten doesn't usually add much sail tension anyway.
Maybe even try more tension if all this fails, as sometimes particularly "Neil Pryde race sails" have more shape here due to our booms being bottom mounted and this pulls differently from where the sail designer intended.
Hope this gets you onto the right track. You will love them at higher speeds, as when you sheet out when way overpowered in a gust they twist off and there is absolutely no sail shake. You can sail them in much higher wind conditions and still have full control due to this.
Have fun.