I can reproduce it too.
Interesting thing - with Version 8.7.9 the preview is working. So maybe a "fix" after that version was resulting into that issue.

UPDATE: At 8.7.9 there is some Snippet at sysext/frontend/Classes/View/AdminPanelView.php#89 where the admPanel is listening at GP['ADMCMD_simTime']
It seems like this was kicked in later 8.7 LTS Versions - and also in 9.4 there is no occurrence for "ADMCMD_simTime" in the code (reading). So maybe this is a feature? :-P

seems to be related with this issue: https://forge.typo3.org/issues/66793

It seems still broken in 8.7.19 but working on the latest master 9.5.1-dev. Can someone confirm?

I have the same problem.

The Preview dont works on pages with start time.

TYPO3 8.7.19

I can see that the timestamp witch will added to the URL "ADMCMD_simTime=" is 1 hour to small. If i change this value manuel, then the preview works.

To test this from Typo3 backend, i changed the value in class TYPO3\CMS\Backend\Utility\BackendUtility in line 4921:

+3600 added to starttime

$simTime = '&ADMCMD_simTime=' . ($pageInfo['starttime'] + 3600);

--------------------------- UPDATE: ---------------------------

the timestamp added to "ADMCMD_simTime=" looks fine. The Problem starts in TypoScriptFrontendController.

$simTime -= date('Z', $simTime);

This line removes 1 hour in my case :-( When i remove this line for tests. The preview from Backend ("Show") works.

My timezone is Europe/Berlin.

--------------------------- UPDATE 2: ---------------------------

i have tested this with TYPO3 9.5.0 and its not working too.

see new created issue https://forge.typo3.org/issues/86653

Problem:¶

• The page "starttime" is safed in database in current server timezone.
• The AdminPanel uses UTC for preview, wich is adjusted later in
  the TypoScriptFrontendController to server timezone.
• The query parameter ADMCMD_simTime from "page show" use the database
  value without adjustments (server timezone). This value is also be
  adjusted in TypoScriptFrontendController. But it was already in
  server timezone.

The patch change ADMCMD_simTime query parameter also to UTC like
AdminPanel.

Current handling:¶

Startdate: 00:00 15-02-2019

Database: 1550185200 => Server Timezone (In this case Europe/Berlin)
AdminPanel: 1550188800 => UTC
Page show: 1550185200 => Server Timezone (In this case Europe/Berlin)

With patch applied:¶

Startdate: 00:00 15-02-2019

Database: 1550185200 => Server Timezone (In this case Europe/Berlin)
AdminPanel: 1550188800 => UTC
Page show: 1550188800 => UTC

@Steffen, is the fix for master (v9) the same/similar to v8? Then the patch needs to be pushed first to master branch and then it will be backported to v8

I think for v9 there need to be more/different changes. Becouse in v9 the adminpanel dont handles ADMCMD_simTime query parameter at all.
I have already created a new issue for that: https://forge.typo3.org/issues/86653

Hi ! I tested this patch and it works fine on typo3 v8 but only for admin account.
With non-admin account, I get the parent page rendered (instead of 404 before applying the patch)

Is there a solution for that bug ?