This is a me too post.
Sangoma A101DE card.
Same issues as the OP and others here. DAHDI config module 13.0.15
As suggested already, the following makes the card visible in FreePBX and dahdi_scan
Disable DAHDI config module
Reboot
Running “/usr/sbin/wancfg_dahdi” at the cli.
Reboot
Enable DAHDI config mdule
Reboot
Card is now visible in FreePBX!
Also have a call in with the supplier of my appliance so will see what approach they suggest to take.\
Thanks