Inventor 2021 changes the default method for processing Excel spreadsheets through iLogic rules running in Inventor. Previous versions used by default the so-called "COM" model, i.e. they used the true Excel kernel. As of version 2021, the faster internal library "LibXL" is used by default for this approach.
You can change this setting in the dialog "iLogic - detailed configuration" (Tools > Options panel > iLogic – configuration).
It should be taken into account that accessing XLS tables may behave differently in certain situations. Although the LibXL library is significantly faster in reading and writing Excel spreadsheets, it is not a full Excel. For example, it cannot recalculate formulas in table cells. Therefore, if you write a new value using an iLogic macro into Excel, the fields that depend on that value will not be recalculated. This will be performed only after you open that spreadsheet in MS Excel.
Therefore, if you need such functionality, switch the Excel module in the iLogic settings from "Internal" to "COM". You will also need the "COM" setting if you are using the iLogic GoExcel.Automation object.
Usage of LibXL can be disabled by setting the environment variable "UseLibXL" to the value of "False". This will enable Inventor to use methods based on Excel. For controlling Excel access in iLogic rules, use a similar environment variable, "iLogicUseLibXL".