I save doing this prologue quest until after I finish (100%) all Daggerfall Covenant zones.
After completing Bankorai (100% to include side quests) and saving Emeric, I tried starting this quest today (12 Nov, 2023) and the same thing happened to me as the op.
I tried starting it both from the crown store and the scroll located in the mages guild in Daggerfall.

I then tried starting it on a lowbie who hasn't done much of anything (to include talking to the hooded figure and nothing in her faction) which yielded positive results (meaning after starting the quest, Gwendis was waiting for me next to the Evermore wayshrine).

Obviously this bug is related to some content being completed. The character I want to do the quest on has done almost everything, Tamriel-wide.

Thank you for reading

Thanks for posting Verolo--

Although the toon I wanted to do this quest has yet to set foot in The Reach, Gwendis has in-fact appeared at her appointed place next to the Evermore wayshrine, even without starting the prologue quest. Works for me.

I also want to thank the team at ZoS for fixing this.
Although I disagree with a few decisions that have been made in the game starting with High Isle, I still overall love this game and I've noticed the visual enhancements and effects to the environment and spirits as well.

Thanks for reading, thank you Zos and please, Dear Reader, stay safe out there.