SFTP client not working on BSP 3 or 5

SFTP client connects, logs in, and then exits. I’ve seen this only on the poky-based distros, 2.8 worked fine.

strace shows the client failing on an EAGAIN on stdin (fd=0) after writing the sftp> prompt.

I was wondering if anyone else knew anything about this. BSP is 5.2, but I saw this on BSP 3.0 and also with Boot2Qt 5.15.1 (which is based on the same code as 3.x). Never saw with 2.8.6.

Strace output on console:

stat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0), ...}) = 0
fstat64(0, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0), ...}) = 0
write(1, "sftp> ", 6sftp> )                   = 6
read(0, 0x21ef058, 1024)                = -1 EAGAIN (Resource temporarily unavailable)
write(1, "\n", 1
)                       = 1
rt_sigaction(SIGCHLD, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x76c64ba1}, {sa_handler=0x49fe91, sa_mask=~[KILL STOP RTMIN RT_1], sa_flags=SA_RESTORER|SA_RESTART, sa_restorer=0x76c64ba1}, 8) = 0
shutdown(3, SHUT_RDWR)                  = 0
shutdown(3, SHUT_RDWR)                  = 0
close(3)                                = 0
close(3)                                = -1 EBADF (Bad file descriptor)
wait4(19903, NULL, 0, NULL)             = 19903
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=19903, si_uid=0, si_status=0, si_utime=4, si_stime=1} ---
futex(0x76edf490, FUTEX_WAKE_PRIVATE, 2147483647) = 0
exit_group(0)                           = ?
+++ exited with 0 +++

Likely a weak cipher issue.