Driveshaft spline lubrication is more complicated than it seems it should be, not just ours.
The main problems are 2; firstly, distributing the grease from the single entry point equally around all the splines. This is usually done by a circumferential groove under the zerk, or as it appears in the V11 shaft by putting the zerk in the endspace where it can find it's way through everywhere. The other problem is the hydraulic one; if you have a relief in the endspace, the grease finds it's way out without going through the splines. The hydraulic action is what drives the lubricant through the splines. On big heavy stuff like trucks, the pressure isn't an issue because the motion is very slow with little travel- by the time it's left the driveway, the shaft has generally gone through most of it's range of motion and made space. On ours, this may not be the case and that first big bump could hydraulic the shaft and um...interfere with suspension movement. My shaft has the zerk in the middle of the splines, and I'm not sure whether it has a distribution groove or not- but I don't grease the zerk anyway, I disassemble the shaft and apply open gear & cable lube manually. That way I'm assured everything is clean and lubed as it can be. So I'm with Phil on the sealing of the yoke end, and after greasing compressing the suspension manually as much as possible to get the range of motion freed up.