After updating to RouterOS 6.38.5 these lines have been changed.
add dst-address=0.0.0.0/0 level=unique sa-dst-address=...87 sa-src-address=0.0.0.0 src-address=172...72/29 tunnel=yes
becomes:
add dst-address=...87/0 level=unique sa-dst-address=...87 sa-src-address=0.0.0.0 src-address=172..*.72/29 tunnel=yes
The tunnel won’t be set-up any more.
Correcting this via the CLI is not possible. Via the webinterface this can be correct.
Therefore it looks like a CLI issue.