For the time being, we advise that you use Mendeley Cite on Microsoft Word for the Web as this is working as expected.
More information on Mendeley Support
To add in-text references and bibliography into your text, you need the Mendeley Cite add-in. It works in Microsoft Word 2016 and newer versions, also in the O365-version (Online).
You can install Mendeley cite directly in Word in the Insert tab: Get add-ins.
Mendeley Cite opens up on the right side of a Word document and it includes three tabs:
Mendeley has almost 7000 citation styles available. If you do no know the name of the citation style you should use, try the form on the Search by example site.
You can edit your in-text references by clicking on them. This activates the blue frames around the citation and opens the editing options on the right-hand side into Mendeley Cite.
if you cannot find a suitable citation style, it is possible to edit an existing style with CSL Editor on the Mendeley homepage. You can use an existing style as a template. CSL Editor saves your edited style to your Mendeley account. From there, you can also share it with other users.