Sep 12 2020
The problem seems to be worse in recent weeks: see https://www.wikidata.org/wiki/Wikidata:Project_chat#Missing_increments_for_new_creates_Items +https://www.wikidata.org/wiki/Wikidata:Contact_the_development_team#Missing_QIDs + https://www.wikidata.org/wiki/Wikidata:Contact_the_development_team#phab:T232620.
Aug 31 2020
Please note that you should take into account not only manual insertions (e.g. https://www.wikidata.org/w/index.php?title=Q957548&diff=1268719940&oldid=1268710970), but also insertions through QuickStatements (e.g. https://www.wikidata.org/w/index.php?title=Q957548&diff=1268710970&oldid=1259272612), OpenRefine and other tools for massive editing.
Jul 9 2020
The issue has misteriously disappeared both in the examples of the property and in the items where it is used, so I close the task.
Jul 8 2020
Jun 18 2020
See also the query https://w.wiki/UUJ, which shows all the parts of the items (there are other properties which look strange).
Jun 17 2020
Jun 1 2020
May 31 2020
May 24 2020
See also https://www.wikidata.org/wiki/Topic:Vkhd578n4cv9ndew: the problem has been persistent in the last month.
May 19 2020
Issue in https://www.wikidata.org/wiki/MediaWiki:Gadget-AuthorityControl.js solved.
May 13 2020
May 7 2020
Apr 19 2020
Feb 10 2020
It was reported by Peter NYC here (https://www.wikidata.org/wiki/User_talk:Ep%C3%ACdosis#Thanks_for_the_Thanks,_but_my_edit_was_a_Fail), who says it only happens when he is logged-in in English Wikipedia. I can't reproduce it too.
Apr 24 2019
Jun 8 2018
In my case I selected "Set a local exception for this global preference" and the box became clickable; then I made one change ad I saved. But when I reloaded the page "Set a local exception for this global preference" was still selected, but the change I made had disappeared. I tried many times, but every time I made the change and then it disappeared.
Dec 9 2017
Aug 3 2016
It's impossible to add or modify statements with "item" datatype.