We have patched ZIM 019 to include a fix for a recent iOS keyboard issue when using ZIM TextInput. They keyboard would show then immediately hide. This has been fixed by setting the HTML text input that ZIM uses to calculate selection and cursor to position:fixed rather than position:absolute.
The CDN has been updated - do a hard refresh and update any local version of ZIM you are using - or get the latest on NPM (19.1.6)
For a history - see Recent Apple iOS keyboard bug with TextInput