I don't think there is much risk at all with the drill report findings, that is merely ceremonial in my view.
I think the market wants to know that the German government (state/local) + Environmental bodies would allow and importantly support a return to potash mining in the area - until that point, they arent valuing the inground value as ever reaching the surface.
In response to this, the below are translated excerpts from the local German newspaper in the area (Thuringer Allgemeine - subscription required), talking about South Harz Potash.
Namely, the Prime Minister (Bodo Ramelow's) support in SHP's activities in the Ohm Mountains: 
The Mayor's support: 
And the old miners support, who were sacked unfairly and why the community is apprehensive for a return to mining (albeit with Prime Ministers support, Mayors support AND now the old miners support
Although there is some against the project (early in Feb) mainly due to the sour taste previously, and the environmental concern (common in European mining projects, there always some form of backlash, although they seem to be turning due to the boards strong messaging of wanting the worlds highest standards for the cleanest mining processes, nothing similar to that of the 90s and the waste that followed.
It is this backlash from those in the environmental departments that is causing this to be so lowly valued by the market imo, even with the clear government support for the project AND the old miners support for the mine to come back online.
I believe the ESG team is doing great work over there now via Town Hall meetings and keeping the community in the light every step of the way, strongly conveying their plans of creating jobs, preserving the environment using world class processes and giving back to the community via grants, i see this as being a success and rerate to follow strongly.
Excerpt from the recent townhall meeting 2 weeks ago: 
*Note, some words may not translate well, the bulk of the team is now German speaking and european based, all words translated by Google.
