The issue is that plantuml is not inferring the relative depths well; plus there may be a bug with not placing the arrow text in such as case.
These two lines imply that stjhcgvt is +2 below lsfwqjhyjkj :
lsfwqjhyjkj -[#8080FF]-> fajspuwgk: lrgzoad
fajspuwgk -[#8080FF]-> stjhcgvt: mavzke
This line implies that visysus is +1 below lsfwqjhyjkj :
lsfwqjhyjkj -[#8080FF]-> visysus: rcevz
But this line implies that visysus and stjhcgvt are at the same level :
visysus -[#8080FF]> stjhcgvt: THIS ISN'T SHOWING
I guess plantuml can't cope well with the contradiction. I mean you might expect it to bump visysus down to the same depth as stjhcgvt to meet the requirement (that's if you assume that -> should bind stronger than -->).
This explains the downward pointing arrow, but not the lack of arrow text, which might also be a bug.
Assuming that -[#8080FF]> isn't a typo (and by OP reaction above it probably was....in which case, as Th. pointed out, the correction is -[#8080FF]->), then a fix is to force a depth of +2 between visysus and lsfwqjhyjkj by using a ---> instead of a -->
lsfwqjhyjkj -[#8080FF]--> visysus: rcevz
See my comment on Th.'s answer for some pictures.
(Interestingly you can put the [#8080FF] anywhere inside the ---> arrow, so --[#8080FF]-> or ---[#8080FF]> also work the same as -[#8080FF]-->).