I can still reproduce the issue, I see a bit longer delay with ETP - Strict, but the blank page occurs also with ETP - Standard or disabled, for me.
Bug 1640426 Comment 3 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
On desktop layout for https://www.splcenter.org/ I would say it seems to be fixed.