Additional info:

I have seen this behavior yesterday and today on three different computers (two Macs and one Windows 10) and with two users. All using Google Chrome. The Windows user had just installed Chrome within the past week. Last week the attachment link in question worked fine on all three machines.

Any replies that tell me to clear my browser cache will be ignored.

Have any other users experienced this? I strongly suspect a bug was introduced with the March version, since we usually get updates around the start of the second week of the month.