Copy pages with gridcontainers lost sorting order

After copying a page with one or more gridcontainers the content elements on the target page have another sorting order.

Example: Source Page:

• 1 Text element (sorting 16)
• 2 Header Element (sorting 32)
• 3 Grid container with two text elements (sorting 512, childs 4 + 8)
• 4 Header element (sorting 768)
• 5 Text element (sorting 1024)

Target page:

• 2 Header Element (sorting 0)
• 1 Text element (sorting 256)
• 3 Grid container with two text elements (sorting 514, childs 513 + 514)
• 4 Header element (sorting 640)
• 5 Text element (sorting 768)

The "2 Header Element" on target page has value 0 in tt_content sorting column.

TYPO3 9.5.3 gridelements 9.0.0