When using the MX3 with Logi Options+, in Excel 365 clicking on a cell sometimes selects the cell next to it (usually to the left, but not always) instead of the cell the pointer is on. Removing LogiOptionsPlusExcelAddin from Excel's COM Add-ins does fix this issue completely, so it's clearly a Logi Options+ issue. This was never an issue with the MX1 and Logitech Options (as far as I know).