After several tries, the dialog box sometimes pops up, but does not show the item being saved as it has always done before, but the item has been saved.

See https://www.zotero.org/support/troubleshooting_translator_issues
If the steps don't solve the issue, we need all the information in the last step.

https://search.proquest.com/results/92906DF743164CDEPQ/1?accountid=4216

Only the little selection boxes (for the yellow folder icon), no accompanying text beside them, but sometimes will save anyway when little boxes are checked.
Error message sometimes says "Troubleshooting translator issues"

See Site Access Limits — ProQuest is one of the sites that blocks you if you try to save too much at once.

Try the alternative approach there or save individual items.

Quoting your email here, since this is where support needs to happen:

So, the same issues outlined in my thread happened at the workshop: When students tried to save a book from WorldCat or an article from ProQuest, they would click the Zotero capture icon (a yellow folder because we were looking at more than one item on a page) and instead of the Notification box appearing and saving the item, the selection box would reappear a second time. They would repeat selecting an item (or several) from the selection box, and although the name of the item being saved would not appear in the Notification box as it typically has in the past (only "Saving to My Library" would appear), Zotero would actually save the item(s) in their Zotero libraries.

In Proquest, the selection box would appear with the little open boxes to place a check mark, but without any text (the names of the items) beside the little boxes. But if you checked some of the little boxes anyway, Zotero would save them in My Library, and the names of the articles and the PDF icon would appear under "Saving to My Library".

As I say above, the most likely explanation is that ProQuest is blocking your IP address (which, depending on the network, could affect all the students) for making too many requests at once. Unfortunately sites can do this in different and unpredictable ways, so it's usually not possible for us to show a clearer error message.

For WorldCat, we would want an example URL, but it could be the same issue.

Thanks for your help. I do not think it is an issue of ProQuest blocking the IP address for making too many requests at once, because it happen when I am probably the only person at this entire university asking for Zotero to save something, and even when I had a class, it consisted of 4 students, and only 1 or 2 were in ProQuest at the same time.

Here is an example URL from WorldCat: https://stfrancisuniversity.on.worldcat.org/search?queryString=gerrymander

This is what happens, not only to me, but to all the students:

Student goes to WorldCat, runs a search, clicks the yellow folder icon. The Zotero Item Selector box comes up as it should. Student makes one or two selections but then the Item Selector box pops up again and student makes selections a second time. Then the Saving Notification box in upper left DOES pop up and says it is "Saving to...(My Library)" but it doesn't say WHAT is being saved (like it typically has in the past). And indeed the item(s) have been saved.

In ProQuest, the Zotero Item Selector box comes up totally blank (white) except for the little black boxes for the user to check off which items he or she wants Zotero to save, i.e. there are no titles beside the little black boxes. However, if the user checks some of the little black boxes anyway, the Notification DOES pop up immediately (no need to do it twice as in WorldCat) and DOES save the checked items AND lists the titles being saved. And indeed the item(s) have been saved.

ProQuest is indeed fixed--no more empty titles--thank you adamsmith.

However, WorldCat is still not working, rather continuing to do what I described above: Zotero does save, but only after the Selection box appears twice and items are selected twice, and then not saying which items are being saved.

D720058475

I was following the instructions to provide you with the Zotero Connector Debug report, and WorldCat worked properly this time. My heartfelt thanks dstillman!

will do

I don't know if you changed anything or not, but I've tried WorldCat a couple times in the interim and it is working now...