It looks like condition determining applicability of `RewriteArgumentsForComCall` in `ExtractSideEffectsFromArguments` doesn't handle extension block members

[AlekseyTs]

            if (indexer.ContainingType.IsComImport)
            {
                RewriteArgumentsForComCall(parameters, actualArguments, refKinds, temps);
            }

See other call site in MakeArguments.