  We show the Harris--Viehmann conjecture under some Hodge--Newton reducibility
condition for a generalization of the diamond of a non-basic Rapoport--Zink
space at infinite level, which appears as a cover of the non-semi-stable locus
in the Hecke stack. We show also that the cohomology of the non-semi-stable
locus with coefficient coming from a cuspidal Langlands parameter vanishes. As
an application, we show the Hecke eigensheaf property in Fargues' conjecture
for cuspidal Langlands parameters in the GL(2)-case.
