Installer freezes after asking for root password on Kubuntu

Installer for my application works fine when installing in user's home directory (or anywhere he has write access), but when trying to install in for example /opt, user is asked for root password, which I provide and then the installer freezes. I can only kill it.

You can have a look the installer file here: https://www.dropbox.com/s/wumy3l43pgjbzso/InstallSQLiteStudio-3.1.1?dl=0

And here is output from installer run with -v option:

$ ./InstallSQLiteStudio-3.1.1 -v
IFW Version: "2.0.5"
Build date: "Mar 20 2017"
Installer Framework SHA1: "9735faf"
[0] Language: pl-PL
[0] Arguments: ./InstallSQLiteStudio-3.1.1, -v
[0] Operations sanity check succeeded.
[0] Resource tree:
[0] :/translations
[0] :/translations/de.qm
[1] :/translations/en.qm
[1] :/translations/fr.qm
[1] :/translations/ja.qm
[2] :/translations/it.qm
[2] :/translations/pl.qm
[3] :/translations/ru.qm
[3] :/translations/qt_de.qm
[3] :/translations/qt_fr.qm
[3] :/translations/qt_ja.qm
[4] :/translations/qt_it.qm
[5] :/translations/qt_pl.qm
[5] :/translations/qt_ru.qm
[5] :/translations/zh_CN.qm
[5] :/translations/qt_zh_CN.qm
[5] :/installer.png
[5] :/installer.ico
[5] :/installer.icns
[9] :/metadata
[9] :/metadata/config
[9] :/metadata/config/config-internal.ini
[9] :/metadata/installer-config
[9] :/metadata/installer-config/controller_qs.qs
[9] :/metadata/installer-config/bg_png.png
[9] :/metadata/installer-config/logo_png.png
[9] :/metadata/installer-config/config.xml
[9] :/metadata/rccprojectw29657.qrc
[9] :/metadata/Updates.xml
[51] Loaded control script ":/metadata/installer-config/controller_qs.qs"
[51] Using control script: ":/metadata/installer-config/controller_qs.qs"
[53] Control script callback "IntroductionPageCallback" does not exist.
[2600] Url is: "://metadata/"
[2602] Warning: Component pl.com.salsoft.sqlitestudio specifies \"Default\" property while not being a leaf node. The \"Default\" property will get a \"false\" value.
[2602] Warning: Component pl.com.salsoft.sqlitestudio specifies \"Default\" property while being not checkable. The \"Default\" property will get a \"false\" value.
[2602] Warning: Component pl.com.salsoft.sqlitestudio depends on other components while having children components. This will not work properly.
[2602] Warning: Other components depend on component pl.com.salsoft.sqlitestudio which has children components. This will not work properly.
[2602] Warning: Component pl.com.salsoft.sqlitestudio.plugins specifies \"Default\" property while not being a leaf node. The \"Default\" property will get a \"false\" value.
[2602] Warning: Component pl.com.salsoft.sqlitestudio.plugins depends on other components while having children components. This will not work properly.
[2602] Warning: Other components depend on component pl.com.salsoft.sqlitestudio.plugins which has children components. This will not work properly.
[2606] Control script callback "TargetDirectoryPageCallback" does not exist.
[3407] Control script callback "ComponentSelectionPageCallback" does not exist.
[4550] Tmp and install folder are on the same volume. Volume mount point: "/" Free space available: "12.40 GiB"
[4550] Installation space required: "76.06 MiB" Temporary space required: "0.00 bajtów" Local repository size: "0.00 bajtów"
[4550] Control script callback "ReadyForInstallationPageCallback" does not exist.
[7932] Control script callback "PerformInstallationPageCallback" does not exist.
[7963] backup operation: Mkdir
[7963] \t- arguments: /opt/SQLiteStudio
[7963] Done
[7963] perform operation: Mkdir
[7963] \t- arguments: /opt/SQLiteStudio
[7963] Done
[7963] Fallback: "/tmp/sqls/InstallSQLiteStudio-3.1.1 --startserver PRODUCTION,

,

"
Zakończony
${code}
(the last word means "finished" in Polish language)