Hi Patrick,
Many thanks for your purchase and kind words regarding Suimono. I'm glad to hear you're happy with it. I'm not 100% sure about the cause of some of these issues but I will give some notes below that might help...
Shoreline object... One of the changes from 5.1.3-->5.1.4 was the inclusion of the 'max depth range' setting on the shoreline object. This setting allows better shoreline resolution steps by limiting the depth (in meters) of the shoreline capture, and should be as low as possible for your scene, though the default of 12 is usually sufficient. However, this also affects the threshold in the Depth Range and Shore Range sttings, so these may need to be adjusted up or down accordingly after setting what your max depth range should be.
That being said, if you just get black regardless of the settings you use, than it could possibly be an issue with the terrain shader. I would recommend doing a test where you put a large cube or other shape underneath the water using the default Unity Standard shader, just to see if the shoreline generation picks that up. If it sees the box and not your terrain then you might try temporarily switching to the default Unity terrain shader instead of CTS.
One of the problems I've seen in the past with CTS was that, for some reason (and only in some particular circumstances) the depth generation was somehow failing... which had contributed to the shoreline not generating. The solution in that case was to change or add a proper fallback to the end of the CTS shader that was used... Fallback "Diffuse". This fallback does some magic stuff behind the scenes in Unity (unfortunately) and any time I've seen a weird issue with a Shader adding the fallback "Diffuse" line has very often fixed it.
As for some of the other issues you're seeing with cameras, I recommend setting Suimono to Automatic camera mode. This mode will always track the camera set to 'MainCamera' tag. Make sure that your main scene camera has the 'MainCamera' tag set, and that all other cameras are untagged. Then when switching cameras between third and first person, you should write a method that a) turns off the MainCamera tag on the old camera, and b) turns on the MainCamera tag on the new camera in that order. When Suimono is then set to 'Automatic' camera mode, it should then keep up with the camera changes (as long as you have the correct camera tagged with 'MainCamera'). Any other cameras in your scene (such as possibly a third camera for the inventory camera?) should be marked as untagged always... or at least they shouldn't have the maincamera tag or Suimono might get confused.
I'm not sure why you would have a box in your inventory view... it seems like changing the culling layers should fix that issue... like it should only render your inventory character layer. Are you sure there aren't any other objects in that area or in your UI that might conflict somehow?
I'm not sure why the asset store Purchase Numbers are showing up blank, but it's not the first time I've seen this. It seems to have started around the beginning of the summer when they switched their number formatting around. I did bring it up to the Asset Store at the time, I can't believe it's not fixed yet
Did you receive an email with an Asset Store invoice when you purchased? There might be other numbers listed their that I can use to confirm purchase. Feel free to email me directly at konnichiwa@tanukidigital.com
Let me know if the above helps or if you still run into any trouble.
-Justin Kellis
Tanuki Digital