I am getting a clock after some of my texts... additionally in a group text, others may or may not see my text and vice versa... this happens with all Android users as well as when mixed with Apple.
The clock symbol means that the message is sendiing, so others may not see your texts during that time. You may be in an area with low cell service coverage, which means it would take longer to send messages. The clock should turn into a timestamp and checkmark when the message sends.
I also have this problem and the 'clock' can be clicked to give you the option to change the sent message to MMS instead of the encrypted. Always works for me after doing so.
