HeidiSQL rounds down double values upon insert...select
Apparently HeidiSQL corrupts the table creation code. The proper table creation code is (without bounds after double):

CREATE TEMPORARY TABLE `new_aps` (
  `MinuteStart` datetime NOT NULL,
  `ProxyListID` bigint(20) NOT NULL,
  `SuccessCount` double NOT NULL,
  `UnknownCount` double NOT NULL,
  `FailureCount` double NOT NULL,
  PRIMARY KEY (`ProxyListID`,`MinuteStart`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci


And the proper way to get it is from the database server, rather than HeidiSQL client:

SHOW CREATE TABLE new_aps