jantje
commented
8 years ago I tested it with this list
https://raw.githubusercontent.com/digistump/arduino-boards-index/master/package_digistump_index.json http://downloads.arduino.cc/packages/package_index.json http://arduino.esp8266.com/stable/package_esp8266com_index.json https://github.com/chipKIT32/chipKIT-core/raw/master/package_chipkit_index.json https://cdn.rawgit.com/geolink/opentracker-arduino-board/master/package_opentracker_index.json https://raw.githubusercontent.com/ElektorLabs/arduino/master/package_elektor-labs.com_ide-1.6.6_index.json https://ardhat.github.io/ardhat-board-support/arduino/package_ardhat_index.json https://raw.githubusercontent.com/Quirkbot/QuirkbotArduinoHardware/master/package_quirkbot.com_index.json https://adafruit.github.io/arduino-board-index/package_adafruit_index.json https://per1234.github.io/Ariadne-Bootloader/package_codebendercc_ariadne-bootloader_index.json https://raw.githubusercontent.com/sparkfun/Arduino_Boards/master/IDE_Board_Manager/package_sparkfun_index.json http://panstamp.org/arduino/package_panstamp_index.json https://raw.githubusercontent.com/TKJElectronics/Balanduino/master/package_tkj_balanduino_index.json https://raw.githubusercontent.com/Lauszus/Sanguino/master/package_lauszus_sanguino_index.json https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json http://drazzy.com/package_drazzy.com_index.json https://raw.githubusercontent.com/carlosefr/atmega/master/package_carlosefr_atmega_index.json https://dl.dropboxusercontent.com/u/2807353/femtoCore/package_femtocow_attiny_index.json https://raw.githubusercontent.com/RiddleAndCode/RnCAtmega256RFR2/master/Board_Manager/package_rnc_index.json http://rfduino.com/package_rfduino_index.json https://github.com/Ameba8195/Arduino/raw/master/release/package_realtek.com_ameba_index.json https://raw.githubusercontent.com/Seeed-Studio/Seeeduino-Boards/master/package_seeeduino_index.json http://download.labs.mediatek.com/package_mtk_linkit_index.json http://download.labs.mediatek.com/package_mtk_linkit_smart_7688_index.json https://raw.githubusercontent.com/NicoHood/HoodLoader2/master/package_NicoHood_HoodLoader2_index.json https://raw.githubusercontent.com/OLIMEX/Arduino_configurations/master/package_olimex_index.json http://navspark.mybigcommerce.com/content/package_navspark_index.json https://raw.githubusercontent.com/mikaelpatel/Cosa/master/package_cosa_index.json https://raw.githubusercontent.com/CytronTechnologies/Cytron-Arduino-URL/master/package_cytron_index.json https://www.mattairtech.com/software/arduino/package_MattairTech_index.json http://www.dan-nixon.com/ArduinoTiLDAHardware/package_tilda_index.json http://www.dwengo.org/sites/default/files/package_dwengo.org_dwenguino_index.json http://downloads.sodaq.net/package_sodaq_index.json https://zevero.github.io/avr_boot/package_zevero_avr_boot_index.json https://raw.githubusercontent.com/eightdog/laika_arduino/master/IDE_Board_Manager/package_project_laika.com_index.json https://mcudude.github.io/MightyCore/package_MCUdude_MightyCore_index.json https://lowpowerlab.github.io/MoteinoCore/package_LowPowerLab_index.json https://rawgit.com/hunianhang/nufront_arduino_json/master/package_tl7788_index.json http://downloads.konekt.io/arduino/package_konekt_index.json https://raw.githubusercontent.com/oshlab/Breadboard-Arduino/master/avr/boardsmanager/package_oshlab_breadboard_index.json https://raw.githubusercontent.com/feilipu/feilipu.github.io/master/package_goldilocks_index.json
and the problem did not occur.
But with only https://raw.githubusercontent.com/digistump/arduino-boards-index/master/package_digistump_index.json
it happens
noticed when looking at #393 When https://raw.githubusercontent.com/digistump/arduino-boards-index/master/package_digistump_index.json is loaded the other boards disappear from the preference board selection page.