Are you using the opensprinkler mobile app, or directly accessing the controller using a web browser?
My suggestion is to first try using HTTP GET to see if anything in the log data is wrong, causing it not to be displayed in the UI. To do so, open a browser and copy/paste the following command:
where x.x.x.x is your OpenSprinkler’s IP address, pw= is followed by the MD5 checksum of your password (the one given is for the default password opendoor, if you have changed the password, you can use an online MD5 calculator to calculate the MD5 of your own password), the last part (hist=5) means retrieving log data of the past 5 days. See if the controller returns anything.
It’s possible that the issue may be related to CORs, but do the above first so that we know the log data is valid.