script functions such as `forcegreeting` can only be used on an npc if visited in the same cell within 72 hours. (see https://en.uesp.net/wiki/Morrowind_Mod:ForceGreeting)

i did a little digging and it seems to be a consequence of this patch: https://www.tamriel-rebuilt.org/comment/26255#comment-26255

the real Saylenus is moved to `SaylenusHoldingCell` on first encounter, when the cell grid "Roth Roryn Region -3 -17" is loaded.
if we do not start and complete the dialogues with the skeleton within 72 hours, then the quest is bugged.

it's really easy to run past and miss the skeleton when going from east to west (from Andothren to Omaynis), not to mention its close proximity to Veranzaris.
buying the shovel and 3 dispel potions may also take several days (waiting for merchants to restock).

i also found several bug reports since that patch, possibly related:
https://www.tamriel-rebuilt.org/bugtracker/impossible-interact-saylenus-...
https://www.tamriel-rebuilt.org/bugtracker/cant-talk-saylenus-ramaril-af...
https://www.tamriel-rebuilt.org/bugtracker/saylenus-ramaril-wont-talk-sk...