I just iupdated to 2021a just to lear that ibtwsis no longer supported. There was no announcement... did it ever occur to anyone at Mathworks that quite a few people actually use the IB interface? I guess that I will stick to 2020b
The Trading Toolbox files that are marked to be in file storage are not currently present. Hopefully mathworks submit the files.
As a work around you can copy the interactive brokers toolbox files from R2020 and use within R2021. In R2020 drill down through the Matlab directory folders and find toolboxes, trading toolbox and copy the "@ibtws" folder.
I am guessing the @ibtws folder is what Mathworks will submit to file exchange anyway.