That is a common problem as the packages in launchpad don't have versioned dependencies and if changes to the base classes are made, all depending modules also need to be rebuilt. This problem is probably caused by a change made to IndiTelescope base class on Dec 21 (github.com/indilib/indi/commit/f0e2df680...30b68039a69eaefb8f67) so you need indilib and eqmod that are both newer or older than that commit, the problem triggers when one is older and one newer. Building all packages at the same time with indilib being first to build avoids this, but can't be easily expressed in launchpad recipes it seems.
Try to start Ekos without connecting drivers. Then connect only eqmod to test. If you have a gdb, that would help you understand where the problem is. If you know which version was working before, this can also help finding an offending change. You can also rename the configuration XML to verify it's not the cause. In any case, it means there is still an unsecure execution path in the eqmod driver.