Excel ComboBox (ActiveX Controls) dropdown not functioning

Hello all,

My issue occurs when trying to select the dropdowns for ComboBoxes on this Excel sheet. Everyone else in my department can access and use this sheet without issue. However, when I select any of the ComboBoxes, right-click and left-click cause a phantom dropdown to hover in the cells above the ComboBox without actually opening the dropdown:

I discovered that I can edit the selection from the dropdown if I go to Developer tab > Design Mode > Right-click ComboBox > ComboBox Options > Edit:

This is an un-optimized, time-consuming solution (to say the least) when I should be able to make these same selections by simply left-clicking the dropdowns when not in Design Mode. I'm guessing that this is an issue with some unknown Excel setting since the ComboBoxes only misbehave this way on my laptop across our office. The sheet is unprotected and creating new ActiveX ComboBoxes results in the same dropdown selection issue.

Any help this forum can provide will be greatly appreciated!!