You probably use *.* wildcard. 7-Zip doesn't uses system wildcard mask parser, and 7-Zip doesn't follow that archaic rule, when *.* means any file. 7-Zip treats *.* as any file that have extension. To process all files you must use * wildcard or omit wildcard at all.
Current version of 7-Zip cannot change archive, created with solid option switched on.
Supporting ACE can be implemented, if source code of that format will be available, and if license of source code will allow using that code.