Hello everyone.
Here's the story:
I have been messing around with adding mods to FTB Unleashed recently and discovered that some item recipes for the new mod weren't working properly (some recipe components were being replaced with the MiscPeripherals Computer Backpack), and seemingly random items weren't being added to the game in the first place. After some experimentation, I figured out that Minecraft Forge was reassigning some default item ID's to prevent item conflicts.
As I dug a little deeper, I found that reassigned items tend to have an item id in the 31,700s (31,900 in-game), since Forge reassigns IDs counting backwards from around 32,000 (the maximum value for an item ID). This shouldn't have caused any problems, since Forge seems to try to find the last available open slot for each item. What caught my attention was that there were items from other mods in FTB in that 31,900 ID range, and those items were conflicting with Forge's attempts to reassign item IDs.
The scoop:
It appears that multiple items and blocks in FTB Unleashed v1.1.3 (and possibly other modpacks) have been given "nearly" invalid IDs caused by Forge reassigning default IDs due to conflicts that may have been resolved before the pack was released. I have found that these nearly invalid items and blocks can cause errors with future items being reassigned by Forge. As explained above, items reassigned by Forge generally are in the 31,700s while blocks reassigned are in the 4080s-4090s.
Here is a list of items and blocks that have appear to have been resigned, the ID the item/block, along with an estimation of what the item/block ID should be (all item IDs are listed before shifting):
tag? Would have made this a lot cleaner 
The ID estimations are based on the IDs of the other items in the mod.
I would like to know if the above IDs are intended by the FTB Team, or if this is possibly an error that needs fixing. I will update this post as soon as I know for certain, but before then, I highly recommend against using the above items, as they may be reassigned in a future FTB update.
TL;DR Don't use the items listed in the spoiler, they might have a bad ID and may be changed in an update.
Forum mods, feel free to do anything with this post, as I just wanted to get this info out there for modpack users and the FTB team to know.
Here's the story:
I have been messing around with adding mods to FTB Unleashed recently and discovered that some item recipes for the new mod weren't working properly (some recipe components were being replaced with the MiscPeripherals Computer Backpack), and seemingly random items weren't being added to the game in the first place. After some experimentation, I figured out that Minecraft Forge was reassigning some default item ID's to prevent item conflicts.
As I dug a little deeper, I found that reassigned items tend to have an item id in the 31,700s (31,900 in-game), since Forge reassigns IDs counting backwards from around 32,000 (the maximum value for an item ID). This shouldn't have caused any problems, since Forge seems to try to find the last available open slot for each item. What caught my attention was that there were items from other mods in FTB in that 31,900 ID range, and those items were conflicting with Forge's attempts to reassign item IDs.
The scoop:
It appears that multiple items and blocks in FTB Unleashed v1.1.3 (and possibly other modpacks) have been given "nearly" invalid IDs caused by Forge reassigning default IDs due to conflicts that may have been resolved before the pack was released. I have found that these nearly invalid items and blocks can cause errors with future items being reassigned by Forge. As explained above, items reassigned by Forge generally are in the 31,700s while blocks reassigned are in the 4080s-4090s.
Here is a list of items and blocks that have appear to have been resigned, the ID the item/block, along with an estimation of what the item/block ID should be (all item IDs are listed before shifting):
- Biomes O' Plenty - Moss 4095 -> 1982
- DenPipes - Automatic Emerald Pipe 31739 -> 28939
- Plugins for Forestry - Iron Ring 31740 -> 4099
- DenPipes - Advanced Apiarist Pipe 31741 -> 28940
- Plugins for Forestry - Filled Wooden Bucket 31742 -> 4446
- MiscPeripherals - Computer Engineer's Backpack 31743 -> 26457
The ID estimations are based on the IDs of the other items in the mod.
I would like to know if the above IDs are intended by the FTB Team, or if this is possibly an error that needs fixing. I will update this post as soon as I know for certain, but before then, I highly recommend against using the above items, as they may be reassigned in a future FTB update.
TL;DR Don't use the items listed in the spoiler, they might have a bad ID and may be changed in an update.
Forum mods, feel free to do anything with this post, as I just wanted to get this info out there for modpack users and the FTB team to know.