Subpanel title doesn't change


I try to change subpanel title but it doesn’t change
I got a successful message but the title wasn’t changed
Please see attachment
Look at background path Studio > Contacts > Subpanels > **Certification_test** (here it's change but if I refresh page it doesn't save

I cannot change any other titles

I have ubuntu 20.04
and I just upgrade my SuiteCRM from 7.11.13 to 7.11.15 (The old version has this error too)

upd: some time ago I could change all tittle
ups: if I go custom/Extension/modules/MYMODULENAME/Ext/Layoutdefs
and change:
to my needed name so at this moment, my subpanel was changed to “my new name” and was be able to change via Studio(like my screen above)

this post fixed my problem