So this bug has been occurring to me for i guess some time(i think probably couple of weeks).First i didn't even notice but as it kept happening it was really stressful.It isn't hard to make this bug happen.You throw your R before death and when you die your R should disappear after a moment .This happened every single time, i took some time to search this bug on bug reports page and i found 2 reports of this bug(submitted in a time of 1 month), but riot didn't answer any of them.I also searched for any info of this as being a change(nerf) to Viktor and i didn't find anything in patch notes for patches 7.3, 7.2 and 7.1.I haven't searched for older patches because i'm pretty sure this has not been happening for the last 2 months, but for last couple of weeks(or even a month actually).I am also going to post links of screenshots of my today's custom game where i wanted to be 100% sure this is a real thing.
Also you can check report from Nightrvn Recston that was submitted 21 days ago where he even made a video about it that i am too going to link.
http://prntscr.com/e91fjm - the moment i dropped R(12:05 on timer)
http://prntscr.com/e91g7w - dead and my R is gone(12:07 on timer, no ult that should last 6.5 sec)
https://youtu.be/JQ_eQrF_IiM - video that poslted Nightrvn Recston
http://boards.eune.leagueoflegends.com/en/c/bug-reports-eu/trQ6aWLO-the-big-problem-with-viktor-ultimateeverybody-whos-playing-him-might-to-know-it - post that made Nightrvn Recston
Now i tested this even with classic skin and it is the same but screenshots are not really that good.You can try this for yourself.Now that i actually found out other people have been experiencing this too i am kinda worried because nothing has been done about this for a month now.Therefore i wanted to make detailed report of this bug to try catching riot's attention.This is actually a major problem because Viktor's R can have crucial part in team fight(skirmish or 1v1) even after his death.