Problem selecting multiple elements in one particu...

A colleague and I have developed a report with six pie and bar charts. When I generate an embed version of the report, I encounter a problem with one of the pie charts in the report. The problem is that holding ctrl does not enable me to select multiple slices from the pie. This problem does not seem to affect any of the other pie charts or bar charts in the report. Likewise, the problem is not present in the Desktop or Office 365 version of the report. It's only present for this one pie chart in the online (embed) version of the report. I can't iddentify any settings or schema issues that might be causing the problem. Has anyone else encountered this?