Never heard of a sensor being located to sense a bolt on the back wheel. That would tell a controller that the bike is moving, which should be fairly obvious if the controller is putting out current. Whatever, proximity switches (which is what sensors that detect metal protuberances are called at electrical supplies) do not usually work at 5 to 10 mm distance. The expensive prox sensors can sense 1 mm away, the cheaper ones sense at a distance of a thickness of a sheet of paper. I would first suggest you bend the mount so the sensor misses the bolt by 1 mm. If your wheel wobbles more than that, tighten the spokes on the away side to true (straighten) your wheel.
The sensor on the crank is supposed to sense that you moved the crank with your feet. The torque sensor on the chain is supposed to detect that you are exerting force on the chain with your feet. if either occurs then the controller will provide current if the PAS level is set higher than "zero".
There is no pro rider brand forum. So I doubt if there are experts here on your system.
As their is no country code that matches "ex28sl", I will suggest a US vendor.
www.ebikeling.com has front power wheel 36 v kits that might allow you to salvage your old battery. Buy the 26" or 700 c wheel if either matches your existing wheels. His 26" wheel kit is showing $180 today. Look at the tire side for the nominal size of your tire & wheel. Don't buy the fat tire kit unless your bike has fat 3" or bigger tires. If you live in another country, use vendors with stock located in that country. If your wheel is a different size, buy a power wheel kit with that size wheel. I looked for kits with motor, controller, switched brake handles, display, PAS level switch, and magnet wheel & sensor.
I'm riding an ebikeling 48 v front wheel geared hub motor kit that I bought in 2017. I have about 4000 miles on it. It does require retightening the motor cover screws occasionally. Use blue locktite on them, that reduces the number of times you have to retighten screws. I've done it twice. The display fogged up in the rain; I don't use it.
If your pro rider motor drags with the power off, you could convert any other bicycle from a charity resale shop or flea market, to an electric bike. I suggest buying one with disk brakes, as those work in the rain. Rim brakes caused an accident for me one time, in the rain. Using power tools to make brackets, use safety glasses. You'll see the controller mounted under my seat on the bike left, with SPAM can lids and machine screws. The battery is mounted on the front with 3/4"x1/8" aluminum angle, and machine screws. Elastic stop nuts keep the machine screws tight after you've installed them. I bought my stainless steel nuts & bolts at mcmaster.com Use insulated bullet connectors or insulated spade lugs to connect the battery to the controller. Reverse the sex of + & - connector so you can't plug the battery in backwards. Pull test crimp terminals after installation. You may need a crank arm puller to remove a bolted on crank arm to put a magnet disk on it. I had a 1 piece crank, and had to remove a pedal and modify the hole in the magnet disk to get it to fit on. I had to use wood wedges & glue as the hole did not fit a 1990's crank arm correctly.
