Negative values for obj_id: SELECT statements throwing errors in query editor

Hi,

I'm using pgAdmin 4.12 in desktop mode on Win 10 1809, databases are 10.9 on CentOS 7.6. When executing any SELECT in the query editor, I get no data but the following error message:
Operator does not exist: - oid

I understand that converting the negative value of attrelid causes that error (full internal statement below, apparently by \web\pgadmin\tools\sqleditor\templates\sqleditor\sql\default\primary_keys.sql):

SELECT at.attname, at.attnum, ty.typname
FROM pg_attribute at LEFT JOIN pg_type ty ON (ty.oid = at.atttypid)
WHERE attrelid=-1769161114::oid AND attnum =
ANY ((SELECT con.conkey FROM pg_class rel LEFT OUTER JOIN pg_constraint con ON con.conrelid=rel.oid AND con.contype='p' WHERE rel.relkind IN ('r','s','t') AND rel.oid = -1769161114::oid)::oid[])

Strange enough, showing the first 100 rows via the menu works as expected and I couldn't reproduce that error neither on a 9.6 database (on Windows localhost) nor with pgAdmin 4.12 running on Linux (also desktop mode); pgAdmin 4.10 and pgAdmin 3 are also working without flaws.

Any ideas or suggestions?

Thanks in advance,
Holger