the strangeness may not be so strange, because both "lv2" and "jack" install targets do have a common sub-target, which is the engine shared objects (libsynthv1.so.*, libsamplv1.so.* and libdrumkv1.so.*) which should be installed and in place (on prefix/lib64/ perhaps) before either target is installed.
specifying no target, or just building both via `make all`, should have been your best sane option.
and if you're trying to package each separately, then it is recommended to build all as in `make` and `make install` and then split the installed files into three packages: a "-common" one with the said shared object, followed by the "-lv2" and "-jack" ones, being the later both dependent on the former.
the strangeness may not be so strange, because both "lv2" and "jack" install targets do have a common sub-target, which is the engine shared objects (libsynthv1.so.*, libsamplv1.so.* and libdrumkv1.so.*) which should be installed and in place (on prefix/lib64/ perhaps) before either target is installed.
specifying no target, or just building both via `make all`, should have been your best sane option.
and if you're trying to package each separately, then it is recommended to build all as in `make` and `make install` and then split the installed files into three packages: a "-common" one with the said shared object, followed by the "-lv2" and "-jack" ones, being the later both dependent on the former.
hth.
cheers