Since there seem to be a number of different threads all reporting instances of players randomly being hit with a loading screen and transitioned to another location as well as crashes being reported I thought it might be helpful to compile a list of the occurrences mentioned so far as well as add my own experience with these bugs. Any reports without a link or source listed are personal experiences.

Crash to Desktop List:

nDSA: (CTD)
While running nDSA myself and another group member both crashed during the Daedric portion of the event.
Additional report for nDSA: (CTD)
https://forums.elderscrollsonline.com/en/discussion/551418/crashes-in-ndsa-it-is-unplayable
Additional report for DSA: (CTD)
https://forums.elderscrollsonline.com/en/discussion/551712/dragon-star-arena-keep-crashing-players-over-and-over-again

Castle Thorn: (CTD)

Mahabahabtha wrote: »

Castle Thorn yesterday: 3 Runs, 3 Blackscreens and crashes to desktop when first time entering the penultimate room.
Other Mate in this 3 particular runs crashes twice while he wanted to leave Blood Twilight room.

https://forums.elderscrollsonline.com/en/discussion/552328/list-of-dungeons-that-markhart-patch-broke

Crypt of Hearts 2:(CTD)

Grandchamp1989 wrote: »

Can confirm crashes in both Crypt 2 and castle thorn for my group

https://forums.elderscrollsonline.com/en/discussion/552328/list-of-dungeons-that-markhart-patch-broke

Elden Hollow 1: (CTD)
https://forums.elderscrollsonline.com/en/discussion/551919/crashing

Fang Lair: (CTD)
Personal Report: Entire group crashed at Caluurion, repeatedly.
Additional Report:
https://forums.elderscrollsonline.com/en/discussion/552120/crash-lair-and-cradle-of-bugs

Moon Hunter Keep: (CTD)
Crash at Mylenne Moon-Caller 1st run, Hedge Maze Guardian in another - 2 different characters.

Scalecaller Peak: (CTD)
https://forums.elderscrollsonline.com/en/discussion/551399/scalecaller-peak-constant-crashes-to-desktop

Wayrest Sewers 1: (CTD)
While running normal daily 2 other players and myself all experience full CTD in turn during the last half of the run - with 2 crashes back to back at the second add wave during the last boss fight.

Wayrest Sewers 2: (CTD)
https://forums.elderscrollsonline.com/en/discussion/552328/list-of-dungeons-that-markhart-patch-broke
Additional Report: (CTD/Hang)
https://forums.elderscrollsonline.com/en/discussion/552533/pc-repeatable-game-crashes-when-fighting-garron-boss-in-wayrest-sewers-ii-dungeon

Battlegrounds: (CTD)
https://forums.elderscrollsonline.com/en/discussion/552391/crashes-to-desktop-while-in-bg-cant-play

Unstable Wall of Frost: (CTD)
https://forums.elderscrollsonline.com/en/discussion/551153/when-unstable-wall-of-frost-casted-makes-me-crash-to-desktop

Loading Screen List:

While doing the Harrowstorm at Old Karth I eventually found myself needing to use a soul gem, however I was then presented with a loading screen and when it was gone my character was at the Giant's Coast Wayshrine. (LS)

Selene's Web: (LS)
https://forums.elderscrollsonline.com/en/discussion/551163/bug-selenes-web-unplayable-because-ls-keep-porting-players-back-to-beginning-of-dungeon

Blackheart Haven: (LS)
https://forums.elderscrollsonline.com/en/discussion/551334/teleported-to-entrance-mid-boss-fight-in-blackheart-haven

White Gold Tower: (Teleport - possible LS, not enough information in report)
https://forums.elderscrollsonline.com/en/discussion/551419/white-gold-tower-teleported-out-of-map

Veteran Sunspire: (Teleport - possible LS, not enough information in report)
https://forums.elderscrollsonline.com/en/discussion/551416/tank-ported-back-to-entrance-in-vss-during-fight

Cyrodiil: (LS)
https://forums.elderscrollsonline.com/en/discussion/551090/getting-randomly-ported-back-to-the-main-gates-in-cyrodiil

[Edits for readability and inclusion of additional reports]