Same here with Xubuntu 21.04 which I am running as a VM in KVM/QEMU and have the same problem - almost.
If I type 1/2 it does not autocorrect to ½ unless I highlight it in the text then go to Tools -> Autocorrect -> Apply when the change occurs.
However, if I try to repeat that with a second typing of 1/2, highlight it, and again go through the Tools -> Autocorrect -> Apply, nothing happens.
Once and only once it happens, not automatically as it does in Xubuntu 20.04 with the same LO version 7.1.2.2.
Same here with Xubuntu 21.04 which I am running as a VM in KVM/QEMU and have the same problem - almost.
If I type 1/2 it does not autocorrect to ½ unless I highlight it in the text then go to Tools -> Autocorrect -> Apply when the change occurs.
However, if I try to repeat that with a second typing of 1/2, highlight it, and again go through the Tools -> Autocorrect -> Apply, nothing happens.
Once and only once it happens, not automatically as it does in Xubuntu 20.04 with the same LO version 7.1.2.2.